Compilare: user.cpp: In function ‘int main()’: user.cpp:67:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(it = 0 ; it != sol . size () ; ++ it) ~~~^~~~~~~~~~~~~~~~ user.cpp:28:31: warning: ignoring return value of ‘char* fgets(char*, int, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] fgets (pat + 1 , NM , cin); ^ user.cpp:29:29: warning: ignoring return value of ‘char* fgets(char*, int, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] fgets (v + 1 , NM , cin); ^ user.cpp:58:47: warning: ‘z’ may be used uninitialized in this function [-Wmaybe-uninitialized] val2 = 1LL * ((val2 + mod) - 1LL * (z * code (v [p1]) % mod)); ~~^~~~~~~~~~~~~~~ In file included from /usr/include/stdio.h:936:0, from /usr/include/c++/6/cstdio:42, from user.cpp:2: In function ‘char* fgets(char*, int, FILE*)’, inlined from ‘int main()’ at user.cpp:28:31: /usr/include/bits/stdio2.h:261:58: warning: call to ‘__fgets_chk_warn’ declared with attribute warning: fgets called with bigger size than length of destination buffer return __fgets_chk_warn (__s, __bos (__s), __n, __stream); ^ In function ‘char* fgets(char*, int, FILE*)’, inlined from ‘int main()’ at user.cpp:29:29: /usr/include/bits/stdio2.h:261:58: warning: call to ‘__fgets_chk_warn’ declared with attribute warning: fgets called with bigger size than length of destination buffer return __fgets_chk_warn (__s, __bos (__s), __n, __stream); ^