#include <vector>
#include <string>
#include <iostream>
using std::vector;
using std::cin;
using std::cout;
using std::string;
using std::pair;
int main()
{
int count;
string first_pile, second_pile;
cin >> count;
cin >> first_pile >> second_pile;
vector<vector<pair<int, int> > > possibility(count + 1);
for (int i = 0; i <= count; ++i) {
possibility[i].resize(count + 1);
}
possibility[0][0].first = 1;
possibility[0][0].second = 0;
for (int i = 1; i <= count; ++i) {
if (possibility[i - 1][0].first == 0) {
possibility[i][0].first = 0;
} else {
if (first_pile[i - 1] == '0') {
if (possibility[i - 1][0].second <= 0) {
possibility[i][0].first = 1;
possibility[i][0].second = possibility[i - 1][0].second + 1;
} else {
possibility[i][0].first = 0;
}
} else {
if (possibility[i - 1][0].second >= 0) {
possibility[i][0].first = 1;
possibility[i][0].second = possibility[i - 1][0].second - 1;
} else {
possibility[i][0].first = 0;
}
}
}
if (possibility[0][i - 1].first == 0) {
possibility[0][i].first = 0;
} else {
if (second_pile[i - 1] == '0') {
if (possibility[0][i - 1].second <= 0) {
possibility[0][i].first = 2;
possibility[0][i].second = possibility[0][i - 1].second + 1;
} else {
possibility[0][i].first = 0;
}
} else {
if (possibility[0][i - 1].second >= 0) {
possibility[0][i].first = 2;
possibility[0][i].second = possibility[i - 1][0].second - 1;
} else {
possibility[i][0].first = 0;
}
}
}
}
for (int i = 1; i <= count; ++i) {
for (int j = 1; j <= count; ++j) {
possibility[i][j].first = 0;
if (possibility[i - 1][j].first != 0) {
if (first_pile[i - 1] == '0') {
if (possibility[i - 1][j].second <= 0) {
possibility[i][j].first = 1;
possibility[i][j].second = possibility[i - 1][j].second + 1;
continue;
}
} else {
if (possibility[i - 1][j].second >= 0) {
possibility[i][j].first = 1;
possibility[i][j].second = possibility[i - 1][j].second - 1;
continue;
}
}
}
if (possibility[i][j - 1].first != 0) {
if (second_pile[j - 1] == '0') {
if (possibility[i][j - 1].second <= 0) {
possibility[i][j].first = 2;
possibility[i][j].second = possibility[i][j - 1].second + 1;
continue;
}
} else {
if (possibility[i][j - 1].second >= 0) {
possibility[i][j].first = 2;
possibility[i][j].second = possibility[i - 1][j].second - 1;
continue;
}
}
}
}
}
if (possibility[count][count].first == 0) {
cout << "Impossible\n";
// cin >> count;
return 0;
}
vector<int> answer(0);
int i = count, j = count;
while ((i != 0) || (j != 0)) {
answer.push_back(possibility[i][j].first);
if (possibility[i][j].first == 1) {
--i;
} else {
--j;
}
}
for (int k = answer.size() - 1; k >= 0; --k) {
cout << answer[k];
}
// cin >> count;
return 0;
}
