#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: linmiaoling
	Language: C++
	Result: Accepted
	Time:9 ms
	Memory:2072 kb
****************************************************************/