#include <iostream>
#include <vector>
#include <queue>
using namespace std;
pair<int, int> arr[110][110];
pair<int, int> moves[10];
int main() {
    queue<pair<int, int> > q, q1;
    char c, c1;
    int ans = 1e6;
    pair<int, int> p, p1;
    cin >> c >> p.second >> c1 >> p1.second;
    p.first = 8 - c + 'a';
    p1.first = 8 - c1 + 'a';
    q.push(p);
    q1.push(p1);
    moves[0].first = 2;
    moves[0].second = 1;
    moves[1].first = 2;
    moves[1].second = -1;
    moves[2].first = 1;
    moves[2].second = 2;
    moves[3].first = 1;
    moves[3].second = -2;
    moves[4].first = -1;
    moves[4].second = 2;
    moves[5].first = -1;
    moves[5].second = -2;
    moves[6].first = -2;
    moves[6].second = 1;
    moves[7].first = -2;
    moves[7].second = -1;
    while (!q.empty()) {
        pair<int, int> v = q.front();
        q.pop();
        for (int i = 0; i <= 7; ++i) {
            if (v.first + moves[i].first > 0 && v.first + moves[i].first <= 8)
                if (v.second + moves[i].second > 0 && v.second + moves[i].second <= 8)
                    if (arr[v.first + moves[i].first][v.second + moves[i].second].first == 0) {
                        arr[v.first + moves[i].first][v.second + moves[i].second].first = arr[v.first][v.second].first + 1;
                        pair<int, int> k;
                        k.first = v.first + moves[i].first;
                        k.second = v.second + moves[i].second;
                        q.push(k);
                    }
        }
        v = q1.front();
        q1.pop();
        for (int i = 0; i <= 7; ++i) {
            if (v.first + moves[i].first > 0 && v.first + moves[i].first <= 8)
                if (v.second + moves[i].second > 0 && v.second + moves[i].second <= 8)
                    if (arr[v.first + moves[i].first][v.second + moves[i].second].second == 0) {
                        arr[v.first + moves[i].first][v.second + moves[i].second].second = arr[v.first][v.second].second + 1;
                        if (arr[v.first + moves[i].first][v.second + moves[i].second].second == arr[v.first + moves[i].first][v.second + moves[i].second].first)
                            if (arr[v.first + moves[i].first][v.second + moves[i].second].second < ans) {
                                ans = arr[v.first + moves[i].first][v.second + moves[i].second].second;
                                //cout << v.first + moves[i].first << " " << v.second + moves[i].second;
                            }
                        pair<int, int> k;
                        k.first = v.first + moves[i].first;
                        k.second = v.second + moves[i].second;
                        q1.push(k);
                    }
        }
    }
    if (ans == 1e6) {
        cout << -1;
    }
    else
        cout << ans;
}