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#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using PII = pair<int, int>;
template <typename A, typename B>
inline void chmin(A &a, B b) {
  if (a > b) a = b;
}
template <typename A, typename B>
inline void chmax(A &a, B b) {
  if (a < b) a = b;
}
class Union_find {
 private:
  vector<int> par;
  vector<int> rank;
  int n;

 public:
  Union_find(int a) {
    n = a;
    for (int i = 0; i < n; i++) {
      par.push_back(i);
      rank.push_back(0);
    }
  }
  int find(int x) {
    if (par[x] == x) {
      return x;
    } else {
      return par[x] = find(par[x]);
    }
  }
  void unite(int x, int y) {
    x = find(x);
    y = find(y);
    if (x == y) return;
    if (rank[x] < rank[y]) {
      par[x] = y;
    } else {
      par[y] = x;
      if (rank[x] == rank[y]) rank[x]++;
    }
  }
  bool same(int x, int y) { return find(x) == find(y); }
};
class LazySegTree {
 private:
  int n;
  vector<ll> node, lazy;
  vector<bool> lazyFlag;

 public:
  LazySegTree(vector<ll> v) {
    int sz = v.size();
    n = 1;
    while (n < sz) n *= 2;
    node.resize(2 * n - 1, 0);
    lazy.resize(2 * n - 1, 0);
    lazyFlag.resize(2 * n - 1, false);
    for (int i = 0; i < (sz); i++) node[i + n - 1] = v[i];
    for (int i = n - 2; i >= 0; i--)
      node[i] = node[2 * i + 1] + node[2 * i + 2];
  }
  void eval(int k, int l, int r) {
    if (lazyFlag[k]) {
      node[k] += lazy[k] * (r - l);
      if (r - l > 1) {
        lazy[2 * k + 1] += lazy[k];
        lazy[2 * k + 2] += lazy[k];
        lazyFlag[2 * k + 1] = lazyFlag[2 * k + 2] = true;
      }
      lazy[k] = 0;
      lazyFlag[k] = false;
    }
  }
  void add(int a, int b, ll x, int k = 0, int l = 0, int r = -1) {
    if (r < 0) r = n;
    eval(k, l, r);
    if (b <= l || r <= a) return;
    if (a <= l && r <= b) {
      lazy[k] += x;
      lazyFlag[k] = true;
      eval(k, l, r);
    } else {
      add(a, b, x, k * 2 + 1, l, (l + r) / 2);
      add(a, b, x, k * 2 + 2, (l + r) / 2, r);
      node[k] = node[k * 2 + 1] + node[k * 2 + 2];
    }
  }
  ll query(int a, int b, int k = 0, int l = 0, int r = -1) {
    if (r < 0) r = n;
    eval(k, l, r);
    if (b <= l || r <= a) return 0;
    if (a <= l && r <= b) return node[k];
    return query(a, b, k * 2 + 1, l, (l + r) / 2) +
           query(a, b, k * 2 + 2, (l + r) / 2, r);
  }
};
class Bucket {
 private:
  int n, bs, bn;
  vector<ll> data;
  vector<ll> bucket, lazy;
  vector<bool> lazyFlag;

 public:
  Bucket(vector<ll> v, int sz) {
    data = v;
    n = v.size();
    bs = sz;
    bn = (n + bs - 1) / bs;
    data.resize(bn * bs, (ll)1e18);
    bucket.assign(bn, (ll)1e18);
    lazy.assign(bn, 0);
    lazyFlag.assign(bn, 0);
    for (int i = 0; i < (bn); i++) {
      ll minx = (ll)1e18;
      for (int j = 0; j < (bs); j++) {
        chmin(minx, data[i * bs + j]);
      }
      bucket[i] = minx;
    }
  }
  void eval(int k) {
    if (lazyFlag[k]) {
      lazyFlag[k] = false;
      for (int i = (bs * k); i < (bs * (k + 1)); i++) {
        data[i] = lazy[k];
      }
      lazy[k] = 0;
    }
  }
  void update(int s, int t, int x) {
    for (int k = 0; k < (bn); k++) {
      int l = k * bs, r = (k + 1) * bs;
      if (r <= s || t <= l) continue;
      if (s <= l && r <= t) {
        lazyFlag[k] = true;
        bucket[k] = x;
        lazy[k] = x;
      } else {
        eval(k);
        for (int i = (max(s, l)); i < (min(t, r)); i++) {
          data[i] = x;
        }
        bucket[k] = (ll)1e18;
        for (int i = (l); i < (r); i++) {
          chmin(bucket[k], data[i]);
        }
      }
    }
  }
  ll query(int s, int t) {
    ll res = (ll)1e18;
    for (int k = 0; k < (bn); k++) {
      int l = k * bs, r = (k + 1) * bs;
      if (r <= s || t <= l) continue;
      if (s <= l && r <= t) {
        chmin(res, bucket[k]);
      } else {
        eval(k);
        for (int i = (max(s, l)); i < (min(t, r)); i++) {
          chmin(res, data[i]);
        }
      }
    }
    return res;
  }
};
int main(void) {
  cin.tie(0);
  ios::sync_with_stdio(false);
  string a, b, res;
  cin >> a >> b;
  res = string('?', a.size());
  int l = 0, r = a.size() - 1;
  sort(a.begin(), a.end());
  sort(b.begin(), b.end());
  reverse(b.begin(), b.end());
  int al = 0, ar = (a.size() + 1) / 2 - 1;
  int bl = 0, br = (a.size() / 2) - 1;
  for (int i = 0; i < (a.size()); i++) {
    if (i % 2 == 0) {
      if (a[al] < b[bl]) {
        res[l] = a[al];
        l++;
        al++;
      } else {
        res[r] = a[ar];
        r--;
        ar--;
      }
    } else {
      if (a[al] < b[bl]) {
        res[l] = b[bl];
        l++;
        bl++;
      } else {
        res[r] = b[br];
        r--;
        br--;
      }
    }
  }
  cout << res << endl;
}
