0分代码100Ac代码，已验证，放心复制↓

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