#include<bits/stdc++.h>
using namespace std;
int main(){
    double n;
    cin>>n;
    if(n<=100 and n>=85){
        cout<<"A";
    }
    if(n<=84.5 and n>=75){
        cout<<"B";
    }
    if(n<=74.5 and n>=60){
        cout<<"C";
    }
    if(n<=59.5 and n>=30){
        cout<<"D";
    }
    if(n<=29.5 and n>=0){
        cout<<"E";
    }
    return 0;
}

C :

#include<stdio.h>
main()
{
	int x;
	scanf("%d",&x);
	if(x>=90)
		printf("A\n");
		else
	{	  if(x>=80)
			printf("B\n");
		else
		{	if(x>=70)
		      printf("C\n");
		else
	          if(x>=60)
				  printf("D\n");
			  else
				  printf("E\n");
		}

	}
}

C++ :

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