#include<bits/stdc++.h>
using namespace std;
int a[50][50],m,n,mn=INT_MAX,mx=INT_MIN,c;  
int main(){
cin>>n>>m;	
for (int i=1;i<=n;i++){
	for(int j=1;j<=m;j++){
	cin>>a[i][j];	
	}
}
for (int i=1;i<=n;i++){
	for(int j=1;j<=m;j++){
if(a[i][j]<mn) mn=a[i][j];
if(a[i][j]>mx) mx=a[i][j];
}
}



cout<<mx-mn;
	return 0;
}

/**************************************************************
	Problem: 1272
	User: lihean
	Language: C++
	Result: Accepted
	Time:8 ms
	Memory:2084 kb
****************************************************************/