题解

#include<iostream>
using namespace std;
int main(){
    int n;
    while(cin>>n){
        if(n<0||n>100){
            cout<<"Score is error!"<<endl;
        }else if(n>=90){
            cout<<'A'<<endl;
        }else if(n>=80){
            cout<<'B'<<endl;
        }else if(n>=70){
            cout<<'C'<<endl;
        }else if(n>=60){
            cout<<'D'<<endl;
        }else{
            cout<<'E'<<endl;
        }
    }
    return 0;
}