9756 Alaska — WA

Hi,
I am getting WA. Please help me.
Here is my code:

#include <cstdio>
int main()
{
	long n;
	while(scanf("%ld",&n)==1)
	{
		if(n==0) break;
			long station[100000],I,J,fag=1;
    		for(I=0 ; I<n ; I++)
		{
				scanf("%ld",&station[I]);
		}
		for(long i=1 ; i<n ; i++)
		for(long j=0 ; j<n-i ; j++)
		{
			if(station[j]>station[j+1])
			{
				long temp=station[j];
				station[j]=station[j+1];
				station[j+1]=temp;
			}
		}
	
		long dis=0;
		for(J=0 ; J<n-1 ; J++)
		{
				dis=station[J+1]-station[J];
				if(dis>200 || dis<-200 || station[n-1]+200<1422 || station[0]>200)
				{
						fag=0;
						break;
				}
		}

		if(fag==0)
			printf("IMPOSSIBLE\n");
		else
			printf("POSSIBLE\n");
		fag=1;
}
return 0;
}