Help me in solving LPYAS152 problem

help
,
1

My issue

runtime error

My code

#include <stdio.h>
int main() 
{
  int num,i,isPrime=1;
  scanf("%d",num);
  if(num<=1)
  {
  isPrime=0;
  }
  else
  {
    for(i=0;i*i<=num;i++)
     {
      if(num%i==0)
       {
        isPrime=0;
        break;
       }
     }
   }
   if(isPrime)
   {
     printf("Prime",num);
   }
   else
   {
     printf("Not Prime",num);
   }
   return 0;
}

Learning course: Algorithmic Problem Solving
Problem Link: https://www.codechef.com/learn/course/klu-problem-solving/KLUPS00A/problems/LPYAS152