Compilare: main.cpp: In function 'int bfs()': main.cpp:27:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i = 0; i < a[x].size(); ++i) ~~^~~~~~~~~~~~~ main.cpp: In function 'void cale(int, int)': main.cpp:53:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i = 0; i < a[x].size(); ++i) ~~^~~~~~~~~~~~~ main.cpp: In function 'int main()': main.cpp:82:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i = 0; i < a[N].size(); ++i) ~~^~~~~~~~~~~~~