#include <bits/stdc++.h>
#define ll long long
using namespace std;
int main() {
string contaner;
string str;
cin >> str;
cin >> contaner;
ll n = str.find('|');
string str1 = str.substr(0, n);
string str2 = str.substr(n + 1);
ll sz1 = str1.size();
ll sz2 = str2.size();
ll si = contaner.size();
if ((sz1+sz2+si)%2!=0||abs(sz1-sz1)>si) {
cout<<"Impossible"<<endl;
return 0;
}
ll total= (sz1+ sz2+ si)/2;
ll lefind= total-sz1;
cout<<str1+contaner.substr(0,lefind)<<'|'<<str2+contaner.substr(lefind)<<endl;
return 0;
}
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