Compilare: user.cpp: In function ‘int main()’: user.cpp:24:59: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(a[i]-'0'>st.back()-'0' && st.size()+n-i>m && st.size()>0) ^ user.cpp:30:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(st.size()<m) ^