Implementing Structure

#include<stdio.h>
#include<conio.h>
#define sz 20
struct std
{
int r_no;
char name[40];
char add[40];
int m1,m2,m3;
};
void main()
{
struct std s[sz];
int i;
clrscr();
for(i=0;i<sz;i++)
 {
 printf("\nRoll no: ");
 scanf("%d",&s[i].r_no);
 flushall();
 printf("Name: ");
 gets(s[i].name);
 printf("Address: ");
 gets(s[i].add);
 printf("Mark1: ");
 scanf("%d",&s[i].m1);
 printf("Mark2: ");
 scanf("%d",&s[i].m2);
 printf("Mark3: ");
 scanf("%d",&s[i].m3);
 }
printf("\nFailed students' info:\n");
printf("\nRollno Name\t\t\tAddress\t\t\tMark1  Mark2  Mark3");
printf("\n------ ----\t\t\t-------\t\t\t-----  -----  -----");
for(i=0;i<sz;i++)
 if(s[i].m1<40||s[i].m2<40||s[i].m3<40)
  printf("\n%-5d  %-25s%-25s%-7d%-7d%-7d",s[i].r_no,s[i].name,s[i].add,s[i].m1,s[i].m2,s[i].m3);
getch();
}