String Deletion from specified position

Aim:
To insert a substring into a string.

Program:
#include<stdio.h>
#include<conio.h>
#include<string.h>
void main()
{
   char str[80],newstr[80];
   int pos,len,count1=0,
   int i=0,t=0 ;
   clrscr ();
printf("Enter a string:");
gets(str);
while( str[i] != '\0' )
    {
       count1++;
       i++;
    }
printf("\nEnter the position to delete the characters:");
scanf("%d",&pos);
printf("\nEnter the number characters to delete:");
scanf("%d",&len);
t = pos;
for( i=pos+len;i<=count1-len;i++)
  {
       str[t] = substr[i];
          t = t+1;
}
printf("\nNewstring is: %s",str);
}

Program:
Enter a string: hyabundai
Enter the position to delete the characters: 3
Enter the number of characters to delete : 2
Newstring is: hyundai