foo.c:1:9: warning: '#pragma GCC optimize' is not a string or number [-Wpragmas]
 #pragma GCC optimize
         ^~~
foo.c:2:9: warning: '#pragma GCC optimize' is not a string or number [-Wpragmas]
 #pragma GCC optimize
         ^~~
foo.c:3:10: fatal error: cstdio: No such file or directory
 #include <cstdio>
          ^~~~~~~~
compilation terminated.

[Hydro](https://hydro.ac)提供评测服务