#include <bits/stdc++.h>
using namespace std;
long long int n, k, m;
bool pdt(long long int x) {
  long long int sum = x;
  long long int d = k;
  while (x > 0) {
    if (floor(x / d) == 0) break;
    sum += floor(x / d);
    d = d * k;
  }
  if (sum >= n) return true;
  return false;
}
void solve() {
  string s;
  cin >> s;
  vector<char> v;
  char c;
  while (cin >> c) v.push_back(c);
  sort(v.begin(), v.end());
  reverse(v.begin(), v.end());
  n = s.length();
  m = v.size();
  long long int j = 0;
  for (long long int i = 0; i < n; i++) {
    if (j < m) {
      if (s[i] < v[j]) {
        s[i] = v[j];
        j++;
      }
    } else
      break;
  }
  cout << s << "\n";
}
int main() {
  std::ios_base::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  long long int t = 1;
  while (t--) {
    solve();
  }
  return 0;
}
