Compilare: main.cpp: In function 'bool bfs()': main.cpp:48:24: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0; i < G[u].size(); ++i) ~~^~~~~~~~~~~~~ main.cpp: In function 'void solve()': main.cpp:97:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < G[t].size(); ++i) { ~~^~~~~~~~~~~~~