#include <bits/stdc++.h>
using namespace std;
#define int long long
constexpr int N = 1010, M = 10010;
constexpr int inf = 1E18, mod = 100003;
int a[N], b[N], dp[N][N], n, m, edit[N][N];
vector<int> path;
inline void dfs(int i, int j) {
    if(i == 0 && j == 0) {
        return ;
    }
    if(edit[i][j] == 0) {
        dfs(i - 1, j);
    }else if(edit[i][j] == 1) {
        dfs(i - 1, j - 1);
    }else if(edit[i][j] == 2) {
        dfs(i - 1, j - 1);
    }else dfs(i, j - 1);
    path.push_back(edit[i][j]);
} 
inline void Main() {
    int x; 
    while(cin >> x, x != -1) {
        n ++;
        a[n] = x;
    }
    while(cin >> x, x != -1) {
        m ++;
        b[m] = x;
    }
    for (int i = 0; i <= n; i ++) {
        dp[i][0] = i;
        edit[i][0] = 0;
    }
    for (int i = 0; i <= m; i ++) {
        dp[0][i] = i;
        edit[0][i] = 3;
    }
    for (int i = 1; i <= n; i ++) {
        for (int j = 1; j <= m; j ++) {
            if(a[i] == b[j]) {
                dp[i][j] = dp[i - 1][j - 1];
                edit[i][j] = 2;
            }else {
                int op = 3;
                dp[i][j] = dp[i][j - 1] + 1;
                if(dp[i][j] > dp[i - 1][j] + 1) {
                    op = 0;
                    dp[i][j] = dp[i - 1][j] + 1;
                }
                if(dp[i][j] > dp[i - 1][j - 1] + 1) {
                    op = 1;
                    dp[i][j] = dp[i - 1][j - 1] + 1;
                }
                edit[i][j] = op;
            }
        }
    }
    cout << dp[n][m] << '\n';
    dfs(n, m);
    int len = path.size();
    for (int i = 0; i < len; i ++) {
        cout << path[i];
    }
}
signed main() {    
    cin.tie(nullptr)->sync_with_stdio(false);
    int T = 1; 
    while(T --) Main();
    return 0;
}