Revise paste Slide-11(Grade)

#include<stdio.h>
int main()
{
    int N,i=0;
    double a,as,ct,m,f,marks;
    scanf("%d",&N);
    while(N--)
    {
        i++;
        scanf("%lf %lf %lf %lf %lf",&a,&as,&ct,&m,&f);
        marks=a+as+ct+(m*2*0.3)+(f*0.4);
        if(marks>=90 && marks<=100)
            printf("Student %d : A",i);
        else if(marks>=86)
            printf("Student %d : A-",i);
        else if(marks>=82 && marks<85)
            printf("Student %d : B+",i);
        else if(marks>=78 && marks<81)
            printf("Student %d : B",i);
        else if(marks>=74 && marks<77)
            printf("Student %d : B-",i);
        else if(marks>=70 && marks<73)
            printf("Student %d : C+",i);
        else if(marks>=66 && marks<69)
            printf("Student %d : C",i);
        else if(marks>=62 && marks<65)
            printf("Student %d : C-",i);
        else if(marks>=58 && marks<61)
            printf("Student %d : D+",i);
        else if(marks>=55 && marks<57)
            printf("Student %d : D",i);
        else if(marks>=0 && marks<55)
            printf("Student %d : F",i);
        printf("\n");
    }
    return 0;
}