Compilare: user.cpp: In function ‘void solve()’: user.cpp:39:28: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i=1; i<v.size(); i++) ^ user.cpp:45:36: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int j=0; j<c.size(); j++) ^ user.cpp:47:46: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int z=0; z<a[c[j]].size(); z++) ^ user.cpp: At global scope: user.cpp:61:6: warning: ISO C++ forbids declaration of ‘main’ with no type [-Wreturn-type] main() ^