#include <bits/stdc++.h>
using namespace std;

#define MAXN 66000
bool vis[MAXN];
int pre[MAXN];
int st_begin, st_end;
int que[MAXN], tail;
int dis[MAXN];
void Print(int x) {
    cout << 1 + (x - 1) / 4;
    cout << 1 + (x - 1) % 4;
}
void rebu(int x) {
    cout << "staut  =  " << x << ":" << endl;
    for (int i = 1; i <= 16; i++) {
        if (x & (1 << (i - 1))) {
            cout << "1";
        } else {
            cout << 0;
        }
        if (i % 4 == 0)
            cout << endl;
    }
}
void solve(int x) {
    if (x == st_begin)
        return;
    solve(pre[x]);

    int y = pre[x] ^ x;
    int tmp = 1;
    int pos = 1;
    int xx = -1, yy = -1;
    for (int i = 1; i <= 16; i++) {
        if (y & tmp) {
            if (xx < 0)
                xx = pos;
            else {
                yy = pos;
                break;
            }
        }
        tmp <<= 1;
        pos++;
    }
    if (xx > yy) {
        int c = xx;
        xx = yy;
        yy = c;
    }
    Print(xx);
    Print(yy);
    cout << endl;
}

bool judge(int x, int y) {
    for (int i = 0; i < 16; i++) {
        if (x & (1 << i)) {
            if ((y & (1 << i)) == 0) {
                return 1;
            }
        } else {
            if ((y & (1 << i)) != 0) {
                return 0;
            }
        }
    }
    return 0;
}
int main() {
    char c;
    for (int i = 1; i <= 16; i++) {
        cin >> c;

        st_begin = (c - '0') * (1 << (i - 1)) + st_begin;
    }
    for (int i = 1; i <= 16; i++) {
        cin >> c;
        st_end = (c - '0') * (1 << (i - 1)) + st_end;
    }
    memset(pre, -1, sizeof(pre));
    vis[st_begin] = 1;
    que[++tail] = st_begin;

    int cnt = 1;
    int x, y;
    while (tail <= cnt) {
        x = que[tail];

        // rebu(x);
        // cout<<"dis = "<<dis[x]<<endl;
        // cout<<x<<endl;
        // system("pause");
        tail++;
        int ls = 2;
        int rs = 1;
        int us = 16;
        int ds = 1;
        for (int i = 1; i <= 15; i++) {
            if (i % 4 == 0) {
                ls <<= 1;
                rs <<= 1;
                if (i <= 12) {
                    y = x - (x & us) - (x & ds) + ((x & us) >> 4) + ((x & ds) << 4);
                    if (!vis[y]) {
                        vis[y] = 1;
                        pre[y] = x;
                        dis[y] = dis[x] + 1;

                        que[++cnt] = y;
                    }
                    us <<= 1;
                    ds <<= 1;
                }
                continue;
            }
            y = x - (x & ls) - (x & rs) + ((x & ls) >> 1) + ((x & rs) << 1);
            if (!vis[y]) {
                // cout<<(x&ls)<<endl<<(x&rs)<<endl;
                // cout<<((x&ls)>>1)<<endl<<((x&rs)<<1)<<endl;
                // rebu(y);
                // system("pause");
                if (!vis[y]) {
                    que[++cnt] = y;
                }
                vis[y] = 1;
                pre[y] = x;
                dis[y] = dis[x] + 1;
            }
            ls <<= 1;
            rs <<= 1;
            if (i > 12)
                continue;
            y = x - (x & us) - (x & ds) + ((x & us) >> 4) + ((x & ds) << 4);

            if (!vis[y]) {
                if (!vis[y]) {
                    que[++cnt] = y;
                }
                vis[y] = 1;
                pre[y] = x;
                dis[y] = dis[x] + 1;
            }
            us <<= 1;
            ds <<= 1;
        }
    }
    cout << dis[st_end] << endl;
    solve(st_end);
    return 0;
}