Write a code of grading system using Switch---case

#include<stdio.h>
int main()
{
int a,m;
scanf("%d", &a);
m=a<=100 && a>=80?1:a<80 && a>=75?2:a<75 && a>=70?3:a<70 && a>=65?4:a<65 && a>=60?5:a<60 && a>=55?6:a<55 && a>=50?7:a<50 && a>=45?8:a<45 && a>=40?9:10;
switch(m)
{
case 1: printf("A+");
break;
case 2: printf("A");
break;
case 3: printf("A-");
break;
case 4: printf("B+");
break;
case 5: printf("B");
break;
case 6: printf("B-");
break;
case 7: printf("C+");
break;
case 8: printf("C");
break;
case 9: printf("D");
break;
default: printf("Fail");
break;
}

return 0;
}