/in/foo.c:1:9: error: expected '=', ',', ';', 'asm' or '__attribute__' before '<' token
 include <stdio.h>
         ^
/in/foo.c: In function 'main':
/in/foo.c:11:2: warning: implicit declaration of function 'scanf' [-Wimplicit-function-declaration]
  scanf("%d", &x);
  ^~~~~
/in/foo.c:11:2: warning: incompatible implicit declaration of built-in function 'scanf'
/in/foo.c:11:2: note: include '<stdio.h>' or provide a declaration of 'scanf'
/in/foo.c:12:2: warning: implicit declaration of function 'solve' [-Wimplicit-function-declaration]
  solve(x);  
  ^~~~~