#include<bits/stdc++.h>
using namespace std;
int main(){
	int a[110][100]={0},m,n,x,d=0,i,j;
	cin>>m>>n;
	for(i=0;i<n;i++){
		for(j=0;j<m;j++){
			cin>>a[i][j];	
}
}
    x=a[0][0];
    for(i=0;i<n;i++){
		for(j=0;j<m;j++){
			if(a[i][j]>d){
				d=a[i][j];
			}
			if(a[i][j]<x){
				x=a[i][j];
			}
		}
	}
	cout<<d-x;
}

/**************************************************************
	Problem: 1272
	User: lvrenxiang
	Language: C++
	Result: Accepted
	Time:9 ms
	Memory:2072 kb
****************************************************************/