#include <bits/stdc++.h>
#define sz(v) (int)v.size()
#define all(v) v.begin(), v.end()

using namespace std;
using ll = long long;
using pii = pair<int, int>;

struct HPA {
    vector<int> a;
    // HPA(int x=0) {
    //     for(;x;x/=10) a.emplace_back(x%10);
    // }
    HPA(string s) {
        assert(false);
    }

    HPA& operator+=(const HPA& other) {
        a.emplace_back(0);
        for(int i=0;i<sz(a);i++) {
            if(i<sz(other.a)) a[i]+=other.a[i];
            a[i+1]+=a[i]/10;
            a[i]%=10;
        }
        if(sz(a)>1&&a[sz(a)-1]==0) a.pop_back();
        return *this;
    }

    bool operator<(const HPA& other) {
        if(sz(a)!=sz(other.a)) return sz(a)<sz(other.a);
        vector<int> x(a);
        vector<int> y(other.a);
        reverse(all(x));
        reverse(all(y));
        return x<y;
    }
};

struct Cell {
    array<array<char, 2>, 2> a;
    array<int, 3> rowof;
    array<int, 3> colof;

    inline array<char, 2>& operator [] (int x) {
        return a[x];
    }

    Cell() {
        for (int i = 0; i < 3; i++)
            rowof[i] = colof[i] = -1;
    }
};

enum Position {
    L = 0, R = 1
};

void solve() {
    int n; cin >> n;
    
    vector<Cell> cells(n);
    {
        vector<string> grid(2);
        cin >> grid[0] >> grid[1];
        cout << grid[0] << '\n' << grid[1] << '\n';

        for (int i = 0; i < n; i++) {
            for (int row = 0; row <= 1; row++) {
                for (int col = 0; col <= 1; col++) {
                    cells[i][row][col] = grid[row][i * 2 + col];
                }
            }
        }
    };

    // for (int i = 0; i < 2 * n; i++)
    //     cout << cells[i / 2][0][i % 2];
    // cout << "\n";
    // for (int i = 0; i < 2 * n; i++)
    //     cout << cells[i / 2][1][i % 2];
    // cout << "\n";

    for (int i = 0; i < n; i++) {
        for (int row = 0; row <= 1; row++) {
            for (int col = 0; col <= 1; col++) {
                for (int num = 1; num <= 2; num++) {
                    if (cells[i][row][col] == '0' + num) {
                        cells[i].rowof[num] = row;
                        cells[i].colof[num] = col;
                    }
                }
            }
        }
    }

    // index of the first RIGHT cell
    vector<int> minPart(2, 0);
    vector<int> maxPart(2, n - 1);

    for (int i = 0; i < n; i++) {
        for (int num = 1; num <= 2; num++) {
            // cout << "CELL " << i << " NUM " << num << ' ' << cells[i].colof[num] << '\n';
            if (cells[i].colof[num] == 0)
                minPart[num] = max(minPart[num], i + 1);
            if (cells[i].colof[num] == 1)
                maxPart[num] = min(maxPart[num], i);
        }
    }

    bool hasSolution = true;
    for (int num = 1; num <= 2; num++) {
        // cout << "MINMAX PARTS " << num << ' ' << minPart[num] << ' ' << maxPart[num] << '\n';
        if (minPart[num] > maxPart[num])
            hasSolution = false;
    }

    if (!hasSolution) {
        cout << "impossible\n";
        return;
    }

    auto construct = [&](array<int, 3> parts) {
        string toprow(2 * n, '?');
        for (int i = 0; i < n; i++) {
            array<Position, 3> pos;
            for (int num = 1; num <= 2; num++)
                pos[num] = (i < parts[num] ? L : R);

            if (pos[1] == pos[2]) {
                const int p = pos[1];
                if (cells[i].rowof[2] != 1)
                    toprow[i * 2 + p] = '2';
                else
                    toprow[i * 2 + p] = '1';
            }
            else {
                for (int num = 1; num <= 2; num++)
                    if (cells[i].rowof[num] != 1)
                        toprow[i * 2 + pos[num]] = '0' + num;
            }
        }

        cout << parts[0] << ' ' << parts[1] << '\n';
        cout << toprow << '\n';
    };

    for (int p1 : { minPart[1], maxPart[1] }) {
        for (int p2 : { minPart[2], maxPart[2] }) {
            array<int, 3> parts;
            parts[1] = p1;
            parts[2] = p2;
            construct(parts);
        }
    }
}

signed main() {
#ifndef LOCAL
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
#endif
    int T = 1;
    cin >> T;
    while (T--) solve();
    return 0;
}