#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
#define FOR(I,A,B) for(ll I = ll(A); I < ll(B); ++I)
const ll MOD = 1000000007;
int main(){
  ll a,b,c,d;
  cin >> a >> b;
  cin >> a >> b;
  cin >> c >> d;
  cout << abs(a-c)+abs(d-b) << endl;
}