Compilare: user.cpp: In function ‘void dfs(int, int, int)’: user.cpp:21:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(cost<0 || nod>=s.size()){ ~~~^~~~~~~~~~ user.cpp:27:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=nod+1;i<s.size();++i){ ~^~~~~~~~~ user.cpp: In function ‘int main()’: user.cpp:40:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<s.size();++i) { ~^~~~~~~~~