一道有关c语言的我不会

怎么用switch做？

switch的话，把成绩除以5，case除以5后的结果

#include <stdio.h>
int main()
{
    int score;
    scanf("%d",&score);
    switch(score/5)
    {
        case 20:
        case 19:
        case 18:
        case 17:
            printf("4");
            break;
        case 16:
        case 15:
            printf("3");
            break;
        case 14:
        case 13:
        case 12:
            printf("2");
            break;
        default:
            printf("0");
    }
    return 0;
}