#include<bits/stdc++.h>
using namespace std;
int a[50][50],n,m,mx,mn=INT_MAX;
int main(){
	cin>>n>>m;
	for(int i=1;i<=n;i++){
		for(int j=1;j<=m;j++){
			cin>>a[i][j];
		} 
	}
	for(int i=1;i<=n;i++){
		for(int j=1;j<=m;j++){
			if(mn>a[i][j])mn=a[i][j];
			if(mx<a[i][j])mx=a[i][j];
		} 
	}
	cout<<(mx-mn);
	return 0;
}

/**************************************************************
	Problem: 1272
	User: wuzihang
	Language: C++
	Result: Accepted
	Time:8 ms
	Memory:2084 kb
****************************************************************/