How to use grade of mark in C language

#include <stdio.h>
int main()
{
    float m1, m2, m3, m4, total, per;
    char grade;
    printf("enter marks of 4 subjects : ");
    scanf("%f%f%f%f", &m1, &m2, &m3, &m4);
    total = m1 + m2 + m3 + m4;
    per = total / 4;
    if (per >= 85)
    {
        grade = 'A';
    }
    else if (per >= 70)
    {
        grade = 'B';
    }
    else if (per >= 55)
    {
        grade = 'c';
    }
    else if (per >= 40)
    {
        grade = 'D';
    }
    else
    {
        grade = 'E';
    }
    printf("percentage is %f,grade is %c\n", per, grade);
    return 0;
}