Compilare: user.cpp: In function ‘int main()’: user.cpp:36:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (i=0;i<v[x].size();i++){ ~^~~~~~~~~~~~ user.cpp:46:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (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,10000001,fin); ^