Lucky Number - c

A Lucky Number is a number defined by the following process: Starting with any positive integer, replace the number by the sum of the squares of its digits, and repeat the process until the number equals 1 (where it will stay), or it loops endlessly in a cycle which does not include 1. Those numbers for which this process ends in 1 are lucky numbers.
Example:    19 is a lucky number
12 + 92 = 82
82 + 22 = 68
62 + 82 = 100
12 + 02 + 02 = 1

Write a program to find whether Nandhini would receive the gift voucher on a particular day. Input is the number of likes that her post received on a particular day.

Business Rules:
Print Invalid Input if the input is negative or if the input is greater than 1000000.
Input Format:
Input consists of an integer that corresponds to the number of likes.
Output Format:
Output consists of a string that is either “YES” or “NO” or “Invalid Input”.

Sample Input 1:
19
Sample Output 1:
YES

Sample Input 2:
20
Sample Output 2:
NO

Sample Input 3:
-20
Sample Output 3:
Invalid Input 

Code:
#include<stdio.h>
int main()
{
unsigned int n,t=0,s=0;
scanf("%d",&n);
if(n>0&&n<1000000){
while(n>=9){
   while(n){
   t=n%10;
   t*=t;
   s+=t;
   //printf("%d",s);
   n/=10;
   }
   n=s;
   s=0;
}
if(n==1) printf("YES");
else printf("NO");
}
else printf("Invalid Input");
return 0;
}