#include<bits/stdc++.h>
using namespace std;
int main(){
	int n,m,max=0,i,j,min=10000;
	cin>>n>>m;
	int a[n][m],b[n];
	for(i=0;i<n;i++){
		for(j=0;j<m;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: zouliangyin
	Language: C++
	Result: Accepted
	Time:17 ms
	Memory:2072 kb
****************************************************************/