#include <bits/stdc++.h>
using namespace std;
int main(){
	int i,j,m,n,max=0,min=9999;
	cin>>m>>n;
	int s[10][10];
	for(i=0;i<m;i++){
		for(j=0;j<n;j++){
			cin>>s[i][j];
			if(s[i][j]>max)
				max=s[i][j];
			if(min>s[i][j])
				min=s[i][j];
		}
	}
	cout<<max-min;
	return 0;
	}

/**************************************************************
	Problem: 1272
	User: fzy001
	Language: C++
	Result: Accepted
	Time:10 ms
	Memory:2072 kb
****************************************************************/