#include<bits/stdc++.h>
using namespace std;
int main(){
	int i,j,n,m,d,x,s;
	cin>>n>>m;
	int a[n][m];
	for(i=0;i<n;i++){
		for(j=0;j<m;j++) {
			cin>>a[i][j];
		}
	}
d=a[1][1];
x=a[1][1];
	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];
				}	
		}
	}
	s=d-x;
	cout<<s;
}


/**************************************************************
	Problem: 1272
	User: wuzhijing
	Language: C++
	Result: Accepted
	Time:8 ms
	Memory:2072 kb
****************************************************************/