#include<bits/stdc++.h>
using namespace std;
int main()
{
    int n,m;
    int a[15][15];
    cin >> m >> n;
    for(int i = 0;i<m;i++)
    {
        for(int j = 0;j<n;j++)
        {
            cin>>a[i][j];
        }
    }
    int ma = a[0][0];
    int mi = a[0][0];
    for(int i = 0;i<m;i++)
    {
        for(int j = 0;j<n;j++)
        {
           if(ma < a[i][j])
           {
                ma = a[i][j];
           } 
        } 
    }
    for(int i = 0;i<m;i++)
    {
        for(int j = 0;j<n;j++)
        {
            if(mi > a[i][j])
            {
                mi = a[i][j];
            }
        }
    }
    cout<<ma-mi;
}
/**************************************************************
	Problem: 1272
	User: wuyichen
	Language: C++
	Result: Accepted
	Time:10 ms
	Memory:2072 kb
****************************************************************/