C++ :

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

Python :

# coding=utf-8
x=float(input())
if (x>=85):
    print("A")
if ((x<85) and (x>=75)):
    print("B")
if ((x<75) and (x>=60)):
    print("C")
if ((x<60) and (x>=30)):
    print("D")
if (x<30):
    print("E")

#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;
}