student structure

/* program to display details of n students */
#include<conio.h>
#include<stdio.h>
int main()
{
	int n,i,regno,flag;
	struct student
	{
		int rollno;
		char name[20];
		int mark;
	}s[20];
	printf("Enter no of students: ");
	scanf("%d",&n);
	printf("Enter details of students:");
	for(i=0;i<n;i++)
	{
		printf("\nEnter the rollno:");
		scanf("%d",&s[i].rollno);
		printf("Enter name of student:\n");
		scanf("%s",&s[i].name);
		printf("Enter mark of student:\n");
		scanf("%d",&s[i].mark);
	}
	printf("Enter register number:\n");
	scanf("%d",&regno);
	for(i=0;i<n;i++)
	{
		if(regno==s[i].rollno)
		{
			printf("Details of students:\n");
			printf("\nEnter the rollno:");
			scanf("%d",&s[i].rollno);
			printf("Enter name of student:");
			scanf("%s",&s[i].name);
			printf("Enter mark of student:");
			scanf("%d",&s[i].mark);
		}
		else
		flag=0;
	}
	return 0;
}