#include <bits/stdc++.h>
using namespace std;
#define rep(i,n) for(int i=0;i<n;i++)
const int MOD=1e9+7;
const long long INF = 1LL<<60;
void YN(bool x){
  if(x) cout<<"Yes"<<endl;
  else cout<<"No"<<endl;
}

int main(){
  int64_t A,B,C,D;cin>>A>>B>>C>>D;
  if(A==C||B==D||abs(A-C)+abs(B-D)<4)cout<<1<<endl;
  else cout<<2<<endl;
}