#include<bits/stdc++.h>
using namespace std;
int main(){
	int m,n,i,j,max,min;
	cin>>m>>n;
	int a[n][m];
	for(i=0;i<n;i++)
	{
		for(j=0;j<m;j++)
		{
			cin>>a[i][j];
		}
	}
	max=a[0][0];
	min=a[0][0];
	for(i=0;i<n;i++)
	{
		for(j=0;j<m;j++)
		{
	if(a[i][j]>max) max=a[i][j];
	if(a[i][j]<min) min=a[i][j];		
		}
	}
	cout<<max-min;
	return 0;
}
/**************************************************************
	Problem: 1272
	User: linyuhang
	Language: C++
	Result: Accepted
	Time:9 ms
	Memory:2072 kb
****************************************************************/