UVa 536 - Tree Recovery

// UVa 536 - Tree Recovery

#include <iostream>
#include <string>
using namespace std;

string pre, in;
int i;

void build(int a, int b) {
	if (a <= b) {
		i++;
		int c = in.find(pre[i], a);
		build(a, c - 1);
		build(c + 1, b);
		cout << in[c];
	}
}

int main() {
	while (cin >> pre) {
		cin >> in;
		i = -1;
		build(0, in.length() - 1);
		cout << endl;
	}
	return 0;
}