#include<bits/stdc++.h>
using namespace std;
int a[15][15],n,m,i,j,min_,max_,c;
int main(){
    cin>>m>>n;
    for(i=0;i<n;i++){
        for(j=0;j<m;j++){
            cin>>a[i][j];
        }
    }
    min_=a[0][0];
    max_=a[0][0];
    for(i=0;i<n;i++){
        for(j=0;j<m;j++){
            if(a[i][j]>max_){
                max_=a[i][j];
            }
            if(a[i][j]<min_){
                min_=a[i][j];
            }
        }
    }
    c=max_-min_;
    cout<<c;
}
/**************************************************************
	Problem: 1272
	User: chenjiahui
	Language: C++
	Result: Accepted
	Time:6 ms
	Memory:2072 kb
****************************************************************/