node, 79 bytes

Result

AC

Duration

934ms

Code [DL]

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

stdin

628 212
544 229
191 912
978 773
739 393
544 346
788 869
363 342
177 583
552 795
146 476
399 591
415 553
877 994
296 495
424 443
271 213
334 223
138 357
942 885
922 229
566 664
559 357
755 513
978 877
891 197
733 211
387 378
926 229
914 695
731 839
997 716

stdout

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

stderr

strace

10    execve("/bin/sh", ["/bin/sh", "/root/script", "/volume/CODE"], 0x7ffc69fc4db0 /* 7 vars */) = 0
11    execve("/bin/cat", ["cat", "-"], 0x55a0e09b7d30 /* 7 vars */ <unfinished ...>
12    execve("/usr/bin/node", ["/usr/bin/node", "/volume/CODE"], 0x55a0e09b7d40 /* 7 vars */ <unfinished ...>
11    <... execve resumed>)             = 0
12    <... execve resumed>)             = 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} ---
14    +++ exited with 0 +++
15    +++ exited with 0 +++
16    +++ exited with 0 +++
17    +++ exited with 0 +++
13    +++ exited with 0 +++
18    +++ exited with 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=4, si_stime=1} ---
10    +++ exited with 0 +++