#include <iostream>
#include <cmath>
using namespace std;
int main(int argc, char** argv) {
    int x1, y1, x2, y2;
    while(scanf("%d %d %d %d",&x1,&y1,&x2,&y2)==4){
        if(x1==0 && x2==0 && y1==0 && y2==0) break;
        if(x1==x2 && y1==y2) printf("0\n");
        else if(x1==x2 || y1==y2 || abs(x1-x2)==abs(y1-y2)) printf("1\n");
        else printf("2\n");
    }
    return 0;
}