percentage

#include<stdio.h>
int main()
{
    int p, ch, b, m, c;
    float ptg;

    printf("Physics: ");
    scanf("%d", &p);
    printf("Chemistry: ");
    scanf("%d", &ch);
    printf("Biology: ");
    scanf("%d", &b);
    printf("Math: ");
    scanf("%d", &m);
    printf("Computer: ");
    scanf("%d", &c);

    ptg = ((p+c+b+m+c)/500.0)*100;
    printf("Percentage: %0.2f%%  \n", ptg);

    if(ptg >= 90)
    {
        printf("Grade: A \n");
    }
    else if(ptg >= 80)
    {
        printf("Grade: B");
    }
    else if(ptg >= 70)
    {
        printf("Grade: C");
    }
    else if(ptg >= 60)
    {
        printf("Grade: D");
    }
    else if(ptg >= 40)
    {
        printf("Grade: E");
    }
    else if(ptg < 40)
    {
        printf("Grade: F");
    }

    return 0;

}