#include<bits/stdc++.h>
using namespace std;
int a[200][200]; 
int main(){
    int n,m,c=0,x=10000,i,j;
	cin>>n>>m;
	for(i=1;i<=n;i++){
		for(j=1;j<=m;j++){
			cin>>a[i][j];
		}
	} 
	for(i=1;i<=n;i++){
		for(j=1;j<=m;j++){
			if(c<=a[i][j]){
				c=a[i][j];
			}
			if(x>=a[i][j]){
				x=a[i][j];
			}
		}
	} 
	cout<<c-x;
	return 0;
}

/**************************************************************
	Problem: 1272
	User: xuanhua
	Language: C++
	Result: Accepted
	Time:7 ms
	Memory:2228 kb
****************************************************************/