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

#define QwQ330AwA return 0
#define ll long long

const int N = 4005;

struct SSAM {
	int nxt[N][2];
	void build(string s) {
		s = " " + s;
		int n = s.length() - 1;
		nxt[n + 1][0] = nxt[n + 1][1] = n + 1;
		for (int i = n; i >= 0; i--) {
			memcpy(nxt[i], nxt[i + 1], sizeof(nxt[i + 1]));
			if (i + 1 <= n) nxt[i][s[i + 1] - '0'] = i + 1;
		}
	}
} S, T;

string s, t;
int f[N][N];
bool pre[N][N];
int n, m;

signed main() {
	ios::sync_with_stdio(0);
	cin.tie(0);
	cin >> s >> t;
	S.build(s);
	T.build(t);
	int n = s.length();
	int m = t.length();
	memset(f, 0x3f, sizeof(f));
	f[n + 1][m + 1] = 0;
	for (int i = n + 1; i >= 0; i--) {
		for (int j = m + 1; j >= 0; j--) {
			for (int o = 0; o < 2; o++) {
				if (f[i][j] > f[S.nxt[i][o]][T.nxt[j][o]] + 1) {
					f[i][j] = f[S.nxt[i][o]][T.nxt[j][o]] + 1;
					pre[i][j] = o; 
				}
			}
		}
	}
	int x = 0, y = 0;
	while (x != n + 1 || y != m + 1) {
		cout << pre[x][y];
		int op = pre[x][y];
		x = S.nxt[x][op], y = T.nxt[y][op];
	}
	QwQ330AwA;
}