#include <bits/stdc++.h>
using namespace std ;

int n , m ;
int a[10100][10100] ;

int main ( )
{
	int MAXX = -0x7fffffff ;
	int MINN = 0x7fffffff ;
	cin >> n >> m ;
	for ( int i = 1 ; i <= n ; i ++ ) {
		for ( int j = 1 ; j <= m ; j ++ ) {
			cin >> a[i][j] ;
			MAXX = max ( MAXX , a[i][j] ) ;
			MINN = min ( MINN , a[i][j] ) ;
		}
	}
	cout << MAXX - MINN + 1 ;
	
	
	return 0 ;
}