计算、编写分数的范围

#include <stdio.h>
int main()
{
    int score;
    scanf("%d", &score);

    if (score >= 90)
    {
        printf("chengji dengji 'A'\n");
        return 0;
    }
    else if (score >= 80)
    {
        if (score <= 89)
        {
            printf("chengji dengji 'B'\n");
            return 0;
        }
    }
    else if (score >= 70)
    {
        if (score <= 79)
        {
            printf("chengjidengji 'C'\n");
            return 0;
        }
    }
    else if (score >= 60)
    {
        if (score <= 69)
        {
            printf("chengjidengji 'D'\n");
            return 0;
        }
    }
    else
    {
        printf("chengjidengji 'E'\n");
        return 0;
    }
}