C++ :

#include<iostream>
using namespace std;
int main()
{
	int score;
	cin>>score;
	int t=score/10;
	char c;
	switch (t)
	{
		case 10:
		case 9:	c='A';	break;
		case 8:	c='B';	break;
		case 7:	c='C';	break;
		case 6:	c='D';	break;
		case 5:
		case 4:
		case 3:
		case 2:
		case 1:
		case 0:	c='E';	break;
	}
	cout<<c<<endl;
	return 0;
}