#include<bits/stdc++.h>
using namespace std;
int main()
{
	int max,min,n,m,a[10][10],i=0,j=0;
	cin>>m>>n;
	for(i=0;i<m;i++){
		for(j=0;j<n;j++){
			cin>>a[i][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: houshanglin
	Language: C++
	Result: Accepted
	Time:8 ms
	Memory:2072 kb
****************************************************************/