#include <algorithm>
#include <array>
#include <cmath>
#include <cstdio>
#include <deque>
#include <iomanip>
#include <iostream>
#include <numeric>
#include <optional>
#include <queue>
#include <set>
#include <stack>
#include <unordered_map>
#include <unordered_set>
#include <vector>

using namespace std;

int main() {
    int64_t a, b, c, d;
    cin >> a >> b >> c >> d;
    int32_t ans;
    if (a == c || b == d || (abs(a - c) + abs(b - d) <= 3))
        ans = 1;
    else
        ans = 2;
    cout << ans << endl;
    return 0;
}