"Anna University Semester Credit Calculator"- Programming using C

Program:

#include<stdio.h>
#include<conio.h> 
int mark(int,int);
void main()
{
    int four,three,two,five,m4,m3,m2,m1,tot,totm;
    float gpa;
    clrscr();
    printf("\nHow many Sub has 'credit 5':  ");
    scanf("%d",&five);
    printf("\nHow many Sub has 'credit 4':  ");
    scanf("%d",&four);
    printf("\nHow many Sub has 'credit 3':  ");
    scanf("%d",&three);
    printf("\nHow many Lab Subjects:  ");
    scanf("%d",&two);
    tot=(4*four)+(3*three)+(2*two)+(5*five);
    m4=mark(4,four);
    m3=mark(3,three);
    m2=mark(2,two);
    m1=mark(5,five);
    totm=m4+m3+m2+m1;
    gpa=(float)totm/tot;
    printf("\n\n *********************** \n");
    printf("*                       *\n");
    printf("* Your GPA is: %f *\n",gpa);
    printf("*                       *\n");
    printf(" ***********************");
    getch();
}
int mark(int grade,int num)
{
    int j=1,n,c;
    float i=0;
    char ma;
    c=0;
    while(c<num)
    {
    fflush(0);
    clrscr();
label_a:
    printf("\nEnter the Grade you scored in the \n");
    printf(" 'subject Number-%d' of credit '%d'= ",j,grade);
    scanf("%c",&ma);
    fflush(0);
    switch(ma)
    {
    case 'S': { n=10; break;  }
    case 's': { n=10; break;  }
    case 'A': { n=9;  break;  }
    case 'a': { n=9;  break;  }
    case 'B': { n=8;  break;  }
    case 'b': { n=8;  break;  }
    case 'C': { n=7;  break;  }
    case 'c': { n=7;  break;  }
    case 'D': { n=6;  break;  }
    case 'd': { n=6;  break;  }
    case 'E': { n=5;  break;  }
    case 'e': { n=5;  break;  }
    default:  { printf("\nEnter a valid grade\n");
              goto label_a;
          }
    }
    i=i+(grade*n);
    c++; 
    j++;
    }
    return i;
}

Sample Output: