C program to accept student detail in structure and display it using pointer

#include<stdio.h>
int main()
{   int j;
    struct student{
        int rollno;
        char name[50];
        int marks[3];

    }*ps;
    printf("Enter your rollno: ");
    scanf("%d", &ps->rollno);
    fflush(stdin);
    printf("Enter your name: ");
    scanf("%[^\n]", &ps->name);

    for(j=0;j<3;j++){
    printf("Enter your marks: ");
    scanf("%d", &ps->marks[j]);}
    printf("\nRollNo: %d",ps->rollno);
    printf("\nName: %s",ps->name);

    for(j=0;j<3;j++){
    printf("\nMarks: %d",ps->marks[j]);}
    return 0;
}