#include <stdio.h>
void main() {
    int num;
    printf("Enter score : ");
    scanf("%d", &num);
    switch (num / 10) {
        case 10:
        case 9:
        case 8:
        printf("Grade A\n");
        break;
    case 7:
        printf("Grade B\n");
        break;
    case 6:
        printf("Grade C\n");
        break;
    case 5:
        printf("Grade D\n");
        break;
    default:
        printf("Grade F\n");
        break;
    }
}