#include<stdio.h>
int main(){
	int m,n,i,j;
	scanf ("%d%d",&m,&n);
	int a[m][n];
	for(i=0;i<m;i++){
		for(j=0;j<n;j++){
			scanf("%d",&a[i][j]);	
		}
	} 
	int max = a[0][0],min = a[0][0];
	for(i=0;i<m;i++){
		for(j=0;j<n;j++){ 
			if(a[i][j]>max){
				max = a[i][j];
			}
			if(a[i][j]<min){
				min = a[i][j];
			}
		}
	}
	printf("%d",max-min);
	return 0; 
}

/**************************************************************
	Problem: 1272
	User: admin
	Language: C
	Result: Accepted
	Time:8 ms
	Memory:1144 kb
****************************************************************/