Compilare: user.cpp: In function ‘int main()’: user.cpp:47:38: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j = 0; j < G[i].size(); ++j) { ^ user.cpp:84:31: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < V.size(); ++i) { ^ In file included from /usr/include/c++/4.8/cassert:43:0, from /usr/include/i386-linux-gnu/c++/4.8/bits/stdc++.h:33, from user.cpp:1: user.cpp:92:24: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] assert(V.size() == faces); ^ user.cpp:22:43: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("nowhere-zero.in", "r", stdin); ^ user.cpp:23:45: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("nowhere-zero.out", "w", stdout); ^