#include<bits/stdc++.h>
using namespace std;
int main() {
	int a[10][10]={0},i,j,n,m,x=0,y=0;
	cin>>n>>m;
	for(i=0;i<n;i++){
		for(j=0;j<m;j++){
			cin>>a[i][j];
		}
	} 
	x=a[0][0];
	y=a[0][0]; 
	for(i=0;i<n;i++){
		for(j=0;j<m;j++){
			if(a[i][j]>x) x=a[i][j];
			if(a[i][j]<y) y=a[i][j];
		}
	} 
	cout<<x-y;
}
/**************************************************************
	Problem: 1272
	User: linzihang
	Language: C++
	Result: Accepted
	Time:9 ms
	Memory:2072 kb
****************************************************************/