Compilare: main.cpp: In function 'int main()': main.cpp:56:24: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int it=0;it<val[i].size();it++) ~~^~~~~~~~~~~~~~ main.cpp:62:34: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int g=0;g<need[j].size();g++) ~^~~~~~~~~~~~~~~