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

int main(){

    int x1, y1, x2, y2;
    scanf( "%d %d %d %d", &x1, &y1, &x2, &y2 );
    if( x1 == x2 || y1 == y2 )
        printf( "2\n" );
    else if( abs( x1 - x2 ) == abs( y1 - y2 ) )
        printf( "1\n" );
    else
        printf( "0\n" );

}