Compilare: main.cpp: In function 'int main()': main.cpp:29:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<l[k].size();i++){ ~^~~~~~~~~~~~ main.cpp:30:35: warning: unused variable 'cost' [-Wunused-variable] int nbg=l[k][i].first,cost=l[k][i].second; ^~~~