Compilare: user.cpp: In function ‘int main()’: user.cpp:77:34: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j=0; j<v[i].size(); ++j) ^ user.cpp:46:35: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("dubi.in", "r", stdin); ^ user.cpp:47:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("dubi.out", "w", stdout); ^ user.cpp:49:20: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &n); ^