#include <bits/stdc++.h>

using namespace std;

int main() {
	int a, b, c, d;
	cin >> a >> b >> c >> d;

	bool ok = false;
	for (int dy = -3; dy <= 3; dy++) {
		for (int dx = -3; dx <= 3; dx++) {
			int nx = a + dx;
			int ny = b + dy;
			if (abs(a-nx) + abs(b-ny) <= 3) {
				if (nx == c && ny == d) {
					ok = true;
				}
			}
		}
	}

	if (a == c || b == d) {
		ok = true;
	}

	if (ok) {
		puts("1");
	} else {
		puts("2");
	}

	return 0;
}