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;
}

Enter Marks of 4 Subjects : 80
95
70
60
percentage is 76.250000, Grade is B