Compilare: user.cpp: In function ‘int main()’: user.cpp:44:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (i=0;i<v[nr%MOD].size();i++){ ~^~~~~~~~~~~~~~~~~ user.cpp:54:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int j=0;j<v[x].size();j++){ ~^~~~~~~~~~~~ user.cpp:16:27: warning: ignoring return value of ‘char* fgets(char*, int, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] fgets (s,10000000,fin); ^ user.cpp:17:22: warning: ignoring return value of ‘char* fgets(char*, int, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] fgets (cc,25,fin); ^ user.cpp:29:28: warning: ignoring return value of ‘char* fgets(char*, int, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] fgets (cc+1,25,fin); ^ In file included from /usr/include/stdio.h:936:0, from /usr/include/c++/6/cstdio:42, from user.cpp:1: In function ‘char* fgets(char*, int, FILE*)’, inlined from ‘int main()’ at user.cpp:29:28: /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); ^