make, 98 bytes

Result

INVALID

Duration

1240ms

Code [DL]

SHELL=bash
export STDIN
a:
	@while read s;do echo $${s:$${s:1:1}-$${s:2:1}?4:2:1};done<<<"$$STDIN"

stdin

366 332
144 559
688 483
215 516
131 764
282 119
377 781
864 641
434 331
227 624
977 141
344 517
688 882
338 639
966 667
569 978
819 364
844 466
538 388
179 977
642 283
763 336
787 835
189 845
463 337
198 285
188 288
524 227
646 664
389 693
691 889
181 485

stdout

6
4
8
5
7
1
7
6
3
6
7
4
8
6
6
9
3
4
3
9
2
3
8
8
3
2
8
2
6
6
8
4

stderr

bash: s: -?4:2: syntax error: operand expected (error token is "?4:2")
make: *** [/volume/CODE:4: a] Error 1

strace

10    execve("/bin/sh", ["/bin/sh", "/root/script", "/volume/CODE"], 0x7fff54123a30 /* 7 vars */) = 0
12    execve("/usr/bin/ag_launcher", ["/usr/bin/ag_launcher", "-i", "/usr/bin/make", "-f", "/volume/CODE"], 0x5557693b40a8 /* 7 vars */) = 0
11    execve("/bin/cat", ["cat", "-"], 0x5557693b4028 /* 7 vars */) = 0
12    execve("/usr/bin/make", ["/usr/bin/make", "-f", "/volume/CODE"], 0x55e3bed81da0 /* 8 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} ---
13    execve("/bin/bash", ["bash", "-c", "while read s;do echo ${s:${s:1:1"...], 0x55dd03a92500 /* 11 vars */) = 0
13    +++ exited with 1 +++
12    +++ exited with 2 +++
10    --- SIGCHLD {si_signo=SIGCHLD, si_code=CLD_EXITED, si_pid=12, si_uid=0, si_status=2, si_utime=0, si_stime=0} ---
10    +++ exited with 2 +++