#include <stdio.h>
#include <string.h>
union id
{
    char name[20];
    int roll_no;
};
struct student
{
    union id cand;
    int marks;
};
int main() {
    struct student stud;
    int choice;
    printf("\n you can enter name (or) roll_number of student\n");
    printf("\n do you want to enter the name?(enter1 if yes) or (enter 0 if no):");
    scanf("%d",&choice);
    if(choice==1)
    {
        printf("\n enter the name:");
        scanf("%s",stud.cand.name);
    }
    
    else
    {
        printf("\n enter roll_no");
        scanf("%d",&stud.cand.roll_no);
    }
    printf("\n enter the marks:");
    scanf("%d",&stud.marks);
    if(choice==1)
    printf("\n name:%s",stud.cand.name);
    else
        printf("\n  roll_number:%d",stud.cand.roll_no);
        printf("\n  marks:%d",stud.marks);
        return 0;
        
    }