#include<bits/stdc++.h>
using namespace std;
int main()
{
	long long a,b,c,d;
	double e;
	cin>>a>>b>>c>>d;
	d=floor(10000000.0*(a+b+c/2)/(a+b+c+d)+a);
	if(d>=9900000) cout<<"EX+";
	else if(d>=9800000) cout<<"EX";
	else if(d>=9500000) cout<<"AA";
	else if(d>=9200000) cout<<"A";
	else if(d>=8900000) cout<<"B";
	else if(d>=8600000) cout<<"C";
	else cout<<"D";
	return 0;
} 

求在代码上改