node, 78 bytes

Result

AC

Duration

1082ms

Code [DL]

console.log((""+require("fs").readFileSync(0)).replace(/.+(.)(\1| ).+/g,"$1"))

stdin

467 865
652 784
527 789
366 698
541 117
972 768
566 962
389 911
992 941
522 819
912 115
411 337
881 818
517 112
399 992
641 417
839 937
167 268
331 292
859 997
566 969
846 267
166 639
216 723
814 415
219 337
344 668
766 496
876 449
688 882
512 526
294 654

stdout

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

stderr

strace

15    execve("/bin/sh", ["/bin/sh", "/root/script", "/volume/CODE"], 0x7ffea81c7640 /* 7 vars */) = 0
16    execve("/bin/cat", ["cat", "-"], 0x55f0d9415d30 /* 7 vars */) = 0
16    +++ exited with 0 +++
15    --- SIGCHLD {si_signo=SIGCHLD, si_code=CLD_EXITED, si_pid=16, si_uid=0, si_status=0, si_utime=0, si_stime=0} ---
17    execve("/usr/bin/node", ["/usr/bin/node", "/volume/CODE"], 0x55f0d9415d40 /* 7 vars */) = 0
19    +++ exited with 0 +++
21    +++ exited with 0 +++
22    +++ exited with 0 +++
20    +++ exited with 0 +++
18    +++ exited with 0 +++
23    +++ exited with 0 +++
17    +++ exited with 0 +++
15    --- SIGCHLD {si_signo=SIGCHLD, si_code=CLD_EXITED, si_pid=17, si_uid=0, si_status=0, si_utime=4, si_stime=1} ---
15    +++ exited with 0 +++