golang, 97 bytes

Result

AC

Duration

1649ms

Code [DL]

package main
import."fmt"
func main(){for{a,b:=0,0;Scan(&a,&b);if b%110<9%a{a=b/10};Print(a%10)}}

stdin

565 723
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377 339
576 171
899 598
637 477
215 152
891 794
917 332
676 633
288 871
955 553
628 235
422 893
825 226
477 785
797 971
529 921
995 595
788 732
311 713
463 339
115 558
889 882
233 339
714 662
438 864
331 948
399 332
438 812
413 195
174 714

stdout

51769751368582277958135836813834

stderr

panic: runtime error: integer divide by zero

goroutine 1 [running]:
main.main()
	/tmp/code.go:3 +0x1ec

strace

10    execve("/bin/sh", ["/bin/sh", "/root/script", "/volume/CODE"], 0x7ffc3de33100 /* 7 vars */) = 0
11    execve("/usr/bin/realpath", ["realpath", "/volume/CODE"], 0x5653413f0d18 /* 7 vars */) = 0
11    +++ exited with 0 +++
10    --- SIGCHLD {si_signo=SIGCHLD, si_code=CLD_EXITED, si_pid=11, si_uid=0, si_status=0, si_utime=0, si_stime=0} ---
12    execve("/bin/ln", ["ln", "-sf", "/volume/CODE", "/tmp/code.go"], 0x5653413f0d38 /* 7 vars */) = 0
12    +++ exited with 0 +++
10    --- SIGCHLD {si_signo=SIGCHLD, si_code=CLD_EXITED, si_pid=12, si_uid=0, si_status=0, si_utime=0, si_stime=0} ---
13    execve("/usr/bin/go", ["/usr/bin/go", "build", "-o", "/tmp/code", "/tmp/code.go"], 0x56534315e028 /* 7 vars */) = 0
20    execve("/usr/lib/go/pkg/tool/linux_amd64/compile", ["/usr/lib/go/pkg/tool/linux_amd64"..., "-V=full"], 0xc0002ad040 /* 25 vars */) = 0
21    execve("/usr/lib/go/pkg/tool/linux_amd64/compile", ["/usr/lib/go/pkg/tool/linux_amd64"..., "-V=full"], 0xc00012a410 /* 25 vars */) = 0
25    +++ exited with 0 +++
24    +++ exited with 0 +++
26    +++ exited with 0 +++
23    +++ exited with 0 +++
20    +++ exited with 0 +++
18    --- SIGCHLD {si_signo=SIGCHLD, si_code=CLD_EXITED, si_pid=20, si_uid=0, si_status=0, si_utime=0, si_stime=0} ---
31    +++ exited with 0 +++
27    +++ exited with 0 +++
29    +++ exited with 0 +++
30    +++ exited with 0 +++
21    +++ exited with 0 +++
18    --- SIGCHLD {si_signo=SIGCHLD, si_code=CLD_EXITED, si_pid=21, si_uid=0, si_status=0, si_utime=0, si_stime=1} ---
28    execve("/usr/lib/go/pkg/tool/linux_amd64/asm", ["/usr/lib/go/pkg/tool/linux_amd64"..., "-V=full"], 0xc0002ad2b0 /* 25 vars */) = 0
32    execve("/usr/lib/go/pkg/tool/linux_amd64/asm", ["/usr/lib/go/pkg/tool/linux_amd64"..., "-V=full"], 0xc00012a5b0 /* 25 vars */) = 0
35    +++ exited with 0 +++
36    +++ exited with 0 +++
34    +++ exited with 0 +++
37    +++ exited with 0 +++
28    +++ exited with 0 +++
16    --- SIGCHLD {si_signo=SIGCHLD, si_code=CLD_EXITED, si_pid=28, si_uid=0, si_status=0, si_utime=0, si_stime=0} ---
40    +++ exited with 0 +++
39    +++ exited with 0 +++
38    +++ exited with 0 +++
32    +++ exited with 0 +++
18    --- SIGCHLD {si_signo=SIGCHLD, si_code=CLD_EXITED, si_pid=32, si_uid=0, si_status=0, si_utime=0, si_stime=0} ---
41    execve("/usr/lib/go/pkg/tool/linux_amd64/compile", ["/usr/lib/go/pkg/tool/linux_amd64"..., "-o", "/tmp/go-build243947220/b001/_pkg"..., "-trimpath", "/tmp/go-build243947220/b001=>", "-p", "main", "-complete", "-buildid", "FhQ0pp0HeGW79v-q_XqX/FhQ0pp0HeGW"..., "-goversion", "go1.13.10", "-D", "_/tmp", "-importcfg", "/tmp/go-build243947220/b001/impo"..., "-pack", "-c=2", "/tmp/code.go"], 0xc0003664e0 /* 25 vars */) = 0
45    +++ exited with 0 +++
43    +++ exited with 0 +++
42    +++ exited with 0 +++
44    +++ exited with 0 +++
41    +++ exited with 0 +++
13    --- SIGCHLD {si_signo=SIGCHLD, si_code=CLD_EXITED, si_pid=41, si_uid=0, si_status=0, si_utime=1, si_stime=1} ---
46    execve("/usr/lib/go/pkg/tool/linux_amd64/link", ["/usr/lib/go/pkg/tool/linux_amd64"..., "-V=full"], 0xc00026a410 /* 25 vars */) = 0
47    +++ exited with 0 +++
50    +++ exited with 0 +++
49    +++ exited with 0 +++
48    +++ exited with 0 +++
46    +++ exited with 0 +++
16    --- SIGCHLD {si_signo=SIGCHLD, si_code=CLD_EXITED, si_pid=46, si_uid=0, si_status=0, si_utime=0, si_stime=0} ---
51    execve("/usr/lib/go/pkg/tool/linux_amd64/link", ["/usr/lib/go/pkg/tool/linux_amd64"..., "-o", "/tmp/go-build243947220/b001/exe/"..., "-importcfg", "/tmp/go-build243947220/b001/impo"..., "-buildmode=exe", "-buildid=cbtpbcnYB_niTzOq9LQW/Fh"..., "-extld=gcc", "/tmp/go-build243947220/b001/_pkg"...], 0xc0003669c0 /* 25 vars */) = 0
55    +++ exited with 0 +++
54    +++ exited with 0 +++
53    +++ exited with 0 +++
52    +++ exited with 0 +++
51    +++ exited with 0 +++
33    --- SIGCHLD {si_signo=SIGCHLD, si_code=CLD_EXITED, si_pid=51, si_uid=0, si_status=0, si_utime=21, si_stime=2} ---
17    +++ exited with 0 +++
16    +++ exited with 0 +++
33    +++ exited with 0 +++
22    +++ exited with 0 +++
19    +++ exited with 0 +++
18    +++ exited with 0 +++
15    +++ exited with 0 +++
14    +++ exited with 0 +++
13    +++ exited with 0 +++
10    --- SIGCHLD {si_signo=SIGCHLD, si_code=CLD_EXITED, si_pid=13, si_uid=0, si_status=0, si_utime=5, si_stime=11} ---
56    execve("/bin/cat", ["cat", "-"], 0x5653413f0d08 /* 7 vars */) = 0
57    execve("/tmp/code", ["/tmp/code"], 0x5653413f0cf0 /* 7 vars */) = 0
56    +++ exited with 0 +++
10    --- SIGCHLD {si_signo=SIGCHLD, si_code=CLD_EXITED, si_pid=56, si_uid=0, si_status=0, si_utime=0, si_stime=0} ---
58    +++ exited with 2 +++
61    +++ exited with 2 +++
60    +++ exited with 2 +++
59    +++ exited with 2 +++
57    +++ exited with 2 +++
10    --- SIGCHLD {si_signo=SIGCHLD, si_code=CLD_EXITED, si_pid=57, si_uid=0, si_status=2, si_utime=0, si_stime=1} ---
62    execve("/bin/rm", ["rm", "/tmp/code.go", "/tmp/code"], 0x5653413f0cf0 /* 7 vars */) = 0
62    +++ exited with 0 +++
10    --- SIGCHLD {si_signo=SIGCHLD, si_code=CLD_EXITED, si_pid=62, si_uid=0, si_status=0, si_utime=0, si_stime=0} ---
10    +++ exited with 0 +++