#include <bits/stdc++.h>

using namespace std;

const int inf = 1e9;

const int maxn = 1e3;
int d[maxn][maxn];

int dx[8] = {2, 1, -1, -2, -2, -1, 1, 2};
int dy[8] = {1, 2, 2, 1, -1, -2, -2, -1};

bool is_ok(int x, int y) {
    return x >= 0 && y >= 0 && x < maxn && y < maxn;
}

struct Point {
    int x, y;
    Point() {}
    Point(int x, int y) : x(x), y(y) {}
};

Point pr[maxn][maxn];

void way(Point p) {
    if (pr[p.x][p.y].x == -1)
        return;
    way(pr[p.x][p.y]);
    cout << p.x << ' ' << p.y << '\n';
}

void solve() {
    int x1, y1, x2, y2;
    cin >> x1 >> y1 >> x2 >> y2;
    queue<Point> q;
    q.push({x1, y1});
    d[x1][y1] = 0;
    pr[x1][y1] = {-1, -1};
    while (!q.empty()) {
        Point p = q.front();
        q.pop();
        if (p.x == x2 && p.y == y2)
            break;
        for (int i = 0; i < 8; ++i) {
            int nx = p.x + dx[i];
            int ny = p.y + dy[i];
            if (is_ok(nx, ny) && d[nx][ny] == inf) {
                q.push({nx, ny});
                d[nx][ny] = d[p.x][p.y] + 1;
                pr[nx][ny] = p;
            }
        }
    }
    cout << d[x2][y2] << '\n';
    way({x2, y2});
}

signed main() {
    for (int i = 0; i < maxn; ++i) {
        for (int j = 0; j < maxn; ++j) {
            d[i][j] = inf;
        }
    }
    solve();
}