Compilare: user.cpp: In function ‘int main()’: user.cpp:31:34: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int it=0;it<val.size();it++) ^ user.cpp:40:38: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int k=1;k<=a[0][j];k++) ^ user.cpp:46:34: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<v.size();i++) ^