C :

#include<stdio.h>
#include<stdlib.h>
#define N 10

int main()
{
	int n, k;
	int mim[N] = {999999999};
	int count_n = 0;
	int i, j, k1;
	int c, d; 
	int *temp;
	do
	{
		scanf("%d%d", &n, &k);
		if(n == 0) break;
		int *a = (int *)malloc(n*sizeof(int));
		int **b = (int **)malloc(n*sizeof(int));
		for(i = 0; i < n; i++)
		{
			scanf("%d", &a[i]);
			b[i] = &a[i];
		}
		for(i = 0; i < n-1; i++)
		{
			k1 = i;
			for(j = i; j < n; j++)
			{
				if(*b[k1] > *b[j])
				{
					k1 = j;
				}
			}
			if(k1 != i)
			{
				temp = b[i];
				b[i] = b[k1];
				b[k1] = temp;
			}
		}
		for(i = 0; i < n-1; i++)
		{
			c = *b[i+1] - *b[i];
			d = c*c;
			if(d < mim[count_n])
			{
				mim[count_n] = d;
			}
		}
		count_n++;
	}while(n);
	for(i = 0; i < count_n; i++)
	{
		printf("%d\n", mim[i]);
	}
	return 0;
}