#include<bits/stdc++.h>
using namespace std;
int main(){
  int i,j,n,m;
  int max=0,min=100;
  int a[10][10];
  cin>>n>>m;
  for(i=0;i<n;i++){
  	for(j=0;j<m;j++){
    cin>>a[i][j];
    if(a[i][j]>max) max=a[i][j];
    if(a[i][j]<min) min=a[i][j];
  	}
  } 
 cout<<max-min;

return 0;
}

/**************************************************************
	Problem: 1272
	User: wtq001
	Language: C++
	Result: Accepted
	Time:10 ms
	Memory:2072 kb
****************************************************************/