#include<bits/stdc++.h>
using namespace std;
int main()
{
	int m,n,i,j,max=0,min=900,c;
	cin>>m>>n;
	for(i=0;i<m;i++){
		for(j=0;j<n;j++){
			cin>>c;
			if(c>max) max=c;
			if(c<min) min=c;
		}
	} 
	cout<<max-min;
	return 0;
}

/**************************************************************
	Problem: 1272
	User: zzz
	Language: C++
	Result: Accepted
	Time:12 ms
	Memory:2072 kb
****************************************************************/