#include<stdio.h>

int main(void){
	int n,k,min = 1001,max  = 0,i;
	scanf("%d%d",&n,&k);
	for(i = 1;i <= k;i++){
		scanf("%d",&k);
		if(min > k){min = k;}
		if(max < k){max = k;}
	}
	printf("%d\n",max-min);
	return 0;
}