C :

#include<stdio.h>
char f(int x){
  if(x<60) return 'E';
  if(x>=60&&x<70) return 'D';
  if(x>=70&&x<80) return 'C';
  if(x>=80&&x<90) return 'B';
  return 'A';
}
int main(){
  int a;
  scanf("%d",&a);
  printf("%c",f(a));
  return 0;
}

C++ :

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

Pascal :

var
  n:longint;
begin
  readln(n);
  if n>=90 then writeln('A') else
    if n>=80 then writeln('B') else
      if n>=70 then writeln('C') else
        if n>=60 then writeln('D') else
          writeln('E');
end.

Java :

import java.util.Scanner;

public class Main {
   private static Scanner s = new Scanner(System.in) ;
   
   public static void main(String[] args) {
	  int score = s.nextInt() ;
	  
	  System.out.println(f(score)) ;
   }
   
   public static String f(int score){
	   String temp = "" ;
	   
	   if(score>=90){
		   temp = "A" ;
	   }else if(80<=score&&score<90){
		   temp = "B" ;
	   }else if(70<=score&&score<80){
		   temp = "C" ;
	   }else if(60<=score&&score<70){
		   temp = "D" ;
	   }else if(score<60){
		   temp = "E" ;
	   }
	   return temp ;
   }
}

Python :

a = input()
print 'A' if a >= 90 else 'B' if 80 <= a < 90 else 'C' if 70 <= a < 80 else 'D' if 60 <= a < 70 else 'E'