#include<bits/stdc++.h>
using namespace std;
int main(){
	int n,m,i=0,j=0,a[100][100]={0},d=1,x=1;
	float sun=0;
	cin>>n>>m;
	for(i=0;i<n;i++){
		for(j=0;j<m;j++){
			cin>>a[i][j];
			if(d<=a[i][j]){
				d=a[i][j];
			}
			if(x>=a[i][j]){
				x=a[i][j];
			}
		}
	}
	cout<<d-x;	
}
/**************************************************************
	Problem: 1272
	User: panyuchen
	Language: C++
	Result: Accepted
	Time:10 ms
	Memory:2072 kb
****************************************************************/