10
4 108 114
5 30 155
8 193 197
9 71 169
2 163 166
8 120 144
8 22 151
4 21 166
2 46 127
8 38 51
 20
9 142 172
7 132 256
8 245 315
9 496 496
3 345 362
8 13 162
5 342 470
9 16 488
9 467 482
4 471 478
10 92 224
6 228 261
9 54 167
2 402 409
5 9 10
7 225 360
3 438 483
6 252 342
3 491 493
6 296 367
 1
8 1234567890123 123456789012345

0
3
0
1
3
0
5
16
9
1
 0
0
0
0
4
6
13
7
0
0
1
2
3
0
0
2
12
9
1
4
 774752389568

#include <bits/stdc++.h>
using namespace std;
long long dp[20][(1 << 19) + 2][2];
long long p10[20];
string a, b;
int sz;
long long fun(int pos, int mask, int choto) {
  if (pos == sz) {
    return 0;
  }
  long long &ret = dp[pos][mask][choto];
  if (ret != -1) return ret;
  for (int i = 0; i < sz; i++) {
    if ((mask & (1 << i)) == 0) {
      if (choto == 0) {
        if (a[i] < b[pos])
          ret = max(ret, (long long)(a[i] - '0') * p10[sz - pos - 1] +
                             fun(pos + 1, mask | (1 << i), 1));
        else if (a[i] == b[pos])
          ret = max(ret,
                    (long long)(a[i] - '0') * p10[sz - pos - 1] +
                        fun(pos + 1, mask | (1 << i), 0 | (pos == (sz - 1))));
      } else
        ret = max(ret, (long long)(a[i] - '0') * p10[sz - pos - 1] +
                           fun(pos + 1, mask | (1 << i), 1));
    }
  }
  return ret;
}
int main() {
  cin >> a >> b;
  sort(a.begin(), a.end());
  reverse(a.begin(), a.end());
  if (a.size() < b.size()) {
    cout << a << endl;
    return 0;
  }
  memset(dp, -1, sizeof(dp));
  sz = a.size();
  p10[0] = 1;
  for (int i = 1; i <= 18; i++) p10[i] = p10[i - 1] * 10;
  long long ans = fun(0, 0, 0);
  printf("%lld\n", ans);
  return 0;
}
