c语言———练习题

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

    if (score >    100)
    {
        printf ("you input the wrong scores \n");
        return 0;
    }

    else if (score < 0)
    {
        printf ("you input the wrong scores \n");
        return 0;
    }


    else if (score >= 90)
    {
        printf("the level of grade is 'A' \n ");
    }

    else if (score >= 80)
    {
        if (score <= 89)
        {
            printf ("the level of grade is 'B' \n");
        }
    }
    else if (score >= 70)
    {
        if(score <= 79)
        {
            printf ("the level of grade is 'C' \n ");
        }
    }

    else if (score >= 60)
    {
        if (score <= 69)
        {
            printf ("the level of grade is 'D' \n ");
        }
    }
    else
    {
        printf("the level of grade is 'E' \n ");
    }
    return 0;
}