#include <bits/stdc++.h>
#pragma warning(disable : 4786)
#pragma warning(disable : 4996)
template <class T>
inline T bigmod(T p, T e, T M) {
  long long ret = 1LL;
  for (; e > 0LL; e >>= 1LL) {
    if (e & 1LL) ret = (ret * p) % M;
    p = (p * p) % M;
  }
  return (T)ret;
}
template <class T>
inline T modinverse(T a, T M) {
  return bigmod(a, M - 2, M);
}
using namespace std;
int main() {
  ios::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  string f, l;
  cin >> f >> l;
  string ans1 = "";
  bool bl = false;
  for (int i = 0, j = 0; i < f.length(); i++) {
    if (i == 0) {
      ans1 += f[i];
      continue;
    }
    if (f[i] >= l[j]) {
      ans1 += l[j];
      bl = true;
      break;
    } else {
      ans1 += f[i];
    }
  }
  if (ans1 == f && bl == false) ans1 += l[0];
  cout << ans1;
}
