uva 10407 Simple Division in C

/* ** Finding the largest divisor which leaves the equal remainder for all integers
** I subtract the 1st int from all int, then finding the GCD will make the expectable result
Nur Shuvo,ICE,NSTU
gmail: nurshuvo51@gmail.com */

#include<stdio.h>
#include<stdlib.h>
/*This is the function which finds the GCD of two integers*/
int GCD(int a ,int b)
{
    int temp,d;
    if(a==0) return b;
    if(b==0) return a;
    if(a<b){
        temp=a;
        a=b;
        b=temp;
    }
    int r=a%b;
    return   GCD(b,r);
}
int main()
{
    int i,j,n,g,ara[1050];
    while(scanf("%d",&n)==1&&n!=0){
        i=0;
        ara[i]=n;
        i++;
        while(scanf("%d",&ara[i])==1&&ara[i]!=0){

        ara[i]=abs(ara[i]-ara[0]);
        i++;
        }
        j=0;
        ara[0]=0;   /*It will be zero */
        g=abs(GCD(ara[1],ara[0]));
        /* Finding GCD of all*/
        for(j=2;j<i;j++){
         g=abs(GCD(g,ara[j]));
        }
      /* now printing the GCD of all integers :) */
        printf("%d\n",abs(g));
       }
       return 0;
    }
    /*Thank u for your patience*/