Compilare: user.cpp: In function ‘void read()’: user.cpp:22:28: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i=0; i<s.size(); i++) ^ user.cpp:26:32: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int j=0; j<s.size(); j++) ^ user.cpp: In function ‘void vec(std::pair<int, int>)’: user.cpp:44:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (p.first!=s.size()-1 && s[p.first+1][p.second]!=INF2) ^ user.cpp:46:28: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (p.second!=s.size()-1 && s[p.first][p.second+1]!=INF2) ^ user.cpp: In function ‘void solve()’: user.cpp:52:28: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i=0; i<x.size(); i++) ^ user.cpp: In function ‘void write()’: user.cpp:58:28: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i=0; i<s.size(); i++,cout << '\n') ^ user.cpp:59:35: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int j=0; j<s[i].size(); j++) ^ user.cpp: At global scope: user.cpp:65:6: warning: ISO C++ forbids declaration of ‘main’ with no type [-Wreturn-type] main() ^