Sum of Two Primes : Hacker Rank Solution in C

Solution to below link problem

https://www.hackerrank.com/contests/primary-prime/challenges/is-prime-or-not-2

#include <stdio.h>

#include <string.h>

#include <math.h>

#include <stdlib.h>

int prime(long long int i)

{

            int j;
            for(j=2;j<=sqrt(i);j++)

            {

                        if(i%j == 0)

                                            return 0;

                 }

                return 1;

}

int main()

{

            long long int i,flag=0,n;

            scanf("%lld",&n);

             if(n<=4)

                    printf("%d",-1);

             else if((n-2)%2 !=0 && prime(n-2))

                    printf("%d\t%lld",2,n-2);

             else

            {

                         for(i=3;i< n-i;i=i+2)

                        {

                                    if((n-i)%2 !=0 && prime(i))

                                    {

                                                if(prime(n-i))

                                                 {

                                                            printf("%lld\t%lld",i,n-i);

                                                            flag=1;

                                                            break;

                                                }

                                    }

                        }

                        if(flag == 0)

                                printf("%d",-1);

             }  

 return 0;

}