https://pintia.cn/problem-sets/1556843855285559296/exam/problems/type/7?problemSetProblemId=1556843936151740419&page=0

#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<ll, ll> PII;
typedef vector<long long> VI;
#define int long long
#define INF 0x3f3f3f3f
#define endl '\n'
#define N 200010
const int mod = 1e9 + 7;



void solve() {
    vector<int> a, b;

    int x, y;
    cin >> x;

    while (x != -1) {
        a.push_back(x);
        cin >> x;
    }
    int n = a.size();
    cin >> y;
    while (y != -1) {
        b.push_back(y);
        cin >> y;
    }

    int m = b.size();
    int res = max (n, m);
    vector<int> ans;
    for (int i = 0; i < min(a.size(), b.size()); i ++) {

        if (a[i] == b[i]) {
            res --;
            ans.push_back(2);
        } else ans.push_back(1);
    }
    int len = abs(n - m);

    for (int i = 1; i <= len; i ++) {
        if (n > m) ans.push_back(0);
        else ans.push_back(3);
    }

    cout << res << endl;
    for(auto t : ans)cout << t;



}

signed main() {

    ios::sync_with_stdio(false);
    cin.tie(0), cout.tie(0);

    int T = 1;
//  cin >> T;
    while (T --)

        solve();

    return 0;
}