Compilare: user.cpp: In function ‘int main()’: user.cpp:15:30: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<n.size();++i) cont+=val[n[i]-'0']; ^ user.cpp:21:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<n.size();++i){ ^ user.cpp:23:32: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j=i+1;j<n.size();++j){ ^