答案

#include<bits/stdc++.h>
using namespace std;
int main()
{
int n;
cin>>n;
if(n<=100 && n>=90 ) cout<<"A";
else if(n<=89 && n>=80) cout<<"B";
else if(n<=79 && n>=70) cout<<"C";
else if(n<=69 && n>=60) cout<<"D";
else cout<<"E";
return 0;
}