Compilare: user.cpp: In function ‘int main()’: user.cpp:72:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(it = 0 ; it < sol . size () ; ++ it) ~~~^~~~~~~~~~~~~~~ user.cpp:26:31: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen (in , "r" , stdin); ^ user.cpp:27:33: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen (out , "w" , stdout); ^ user.cpp:28:43: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf ("%s\n%s" , (pat + 1) , (v + 1)); ^ user.cpp:59:36: warning: ‘z’ may be used uninitialized in this function [-Wmaybe-uninitialized] val2 = (((val2 + mod) - (z * code (v [p1]) % mod ))) % mod ; ~~^~~~~~~~~~~~~~~ user.cpp:61:40: warning: ‘z2’ may be used uninitialized in this function [-Wmaybe-uninitialized] val22 = (((val22 + mod2) - (z2 * code (v [p1]) % mod2 ))) % mod2 ; ~~~^~~~~~~~~~~~~~~