Compilare: user.cpp: In function ‘int main()’: user.cpp:38:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (i=0;i<v[nr%MOD].size();i++){ ~^~~~~~~~~~~~~~~~~ user.cpp:48:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int j=0;j<v[x].size();j++){ ~^~~~~~~~~~~~ user.cpp:15:10: warning: unused variable ‘c’ [-Wunused-variable] char c; ^ 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); ^