bcdef
abbbc
 z
y
 reddit
abcdef
 abc
aaa
 y
z
 cbxz
aaaa

bccdb
 z
 dfdeed
 aab
 y
 abac

#include<bits/stdc++.h>



using namespace std;

#define REP(i, a, b) for ( int i=(a); i<(b); i++)

#define clr(a, b) memset ( a, b, sizeof(a))

#define x first

#define y second

const int maxn = 100010;

const int mod = 1e9+7;

typedef pair < int, int > pi;

typedef vector < int > V;

typedef long long ll;

char A[maxn], B[maxn], ans[maxn];



int main() {

	scanf("%s%s", A, B);

	int len = strlen( A );

	sort( A, A+len);

	sort( B, B+len);

	strrev(B);

	int k = 0;

	int u = 0 , v = 0;

	if ( len&1 ) {

		ans[k++] = A[u++];

		while ( k != len ) {

			if ( A[u] < B[v] ) ans[k++] = B[v++], ans[k++] = A[u++];

			else ans[--len] = A[u++], ans[k++] = B[v++];

		}

	}

	else{

		 while ( k != len ) {

			if ( A[u] < B[v] ) ans[k++] = A[u++], ans[k++] = B[v++];

			else ans[--len] = A[u++], ans[k++] = B[v++];

		}

	}

	printf("%s", ans);

	return 0;

}
                      