#include <bits/stdc++.h>
using namespace std;
using namespace chrono;
using used_clock = high_resolution_clock;

int main() {
    using ipair = pair<int,int>;
    const string alphabet = "01?";
    const string no_solution = "-1";
    const auto char_code = [&](char c) { return alphabet.find(c); };
    const auto lsb = [](int x) { return x&1; };
    const auto expected_solution = [&](int a, int b, string s) {
        int n = a+b, m = n-1, l = 0, r = m;
        vector<int> unknown;
        for (; l < r; ++l, --r)
            switch (char_code(s[l])+3*char_code(s[r])) {
            case 0: case 2: case 6:
                if (a < 2)
                    return no_solution;
                s[l] = s[r] = '0', a -= 2; break;
            case 4: case 5: case 7:
                if (b < 2)
                    return no_solution;
                s[l] = s[r] = '1', b -= 2; break;
            case 8:
                unknown.push_back(l); break;
            default:
                return no_solution; }
        if (l == r)
            switch (s[l]) {
            case '0':
                if (a == 0)
                    return no_solution;
                --a; break;
            case '1':
                if (b == 0)
                    return no_solution;
                --b; break;
            default:
                if (lsb(a))
                    s[l] = '0', --a;
                else
                    s[l] = '1', --b; }
        for (auto p: unknown)
            if (a > 1)
                s[p] = s[m-p] = '0', a -= 2;
            else if (b > 1)
                s[p] = s[m-p] = '1', b -= 2;
            else
                return no_solution;
        return s; };
    const auto is_palindrome = [&](int n, const string& s) {
        for (int l = 0, r = n-1; l < r; ++l, --r)
            if (s[l] != s[r])
                return false;
        return true; };
    const auto histogram = [](const string& s) {
        int count[2] = {};
        for (auto c: s)
            if (isdigit(c))
                ++count[c-'0'];
        return ipair(count[0],count[1]); };
    const auto HNS_17502_solution = [&](int a, int b, string s) {
        const int n = a+b, p = lsb(n), q = n>>1;
        if (p == 0 and lsb(a))
            return no_solution;
        int a0 = a, b0 = b;
        const auto [zero,one] = histogram(s);
        if (p) {
            if (lsb(a))
                switch (s[q]) {
                case '1':
                    return no_solution;
                case '?':
                    s[q] ='0', --a; }
            else
                switch (s[q]) {
                case '0':
                    return no_solution;
                case '?':
                    s[q] ='1',  --b; } }
        a -= zero, b -= one;
        bool ok = true;
        for (int l = 0, r = n-1; l < r; ++l, --r) {
            if (s[l] != '?' and s[r] != '?') {
                if (s[l] != s[r]) {
                    ok = false; break; } }
            else if (s[l] != '?' and s[r] == '?') {
                char c = s[l];
                if (c == '0' and a > 0)
                    s[r] = '0', --a;
                else if (c == '0' and a == 0) {
                    ok = false; break; }
                if (c == '1' and b > 0)
                    s[r] = '1', --b;
                else if (c =='1' and b == 0) {
                    ok = false; break; } }
            else if (s[l] == '?' and s[r] != '?') {
                char c = s[r];
                if (c == '0' and a > 0)
                    s[l] = '0', --a;
                else if (c == '0' and a == 0) {
                    ok = false; break; }
                if (c == '1' and b > 0)
                    s[l] = '1', --b;
                else if (c =='1' and b == 0) {
                    ok = false; break; } }
            else if (s[l] == '?' and s[r] =='?') {
                if (a > 1)
                    s[l] = s[r] ='0', a -= 2;
                else if (b > 1)
                    s[l] = s[r] ='1', b -= 2;
                else {
                    ok = false; break; } } }
        if (not ok)
            return no_solution;
        const auto [a1,b1] = histogram(s);
        return a1 == a0 and b1 == b0 and is_palindrome(n,s) ? s : no_solution; };
    uniform_int_distribution<int> uniform_char(0,2);
    mt19937_64 random(used_clock::now().time_since_epoch().count());
    int n, iterations; cin >> n >> iterations;
    uniform_int_distribution<int> uniform_zero(0,n);
    while (iterations--) {
        const int a = uniform_zero(random), b = n-a;
        string s;
        for (int i = 0; i < n; ++i)
            s += alphabet[uniform_char(random)];
        const auto output = HNS_17502_solution(a,b,s);
        const auto correct = expected_solution(a,b,s);
        if (output == correct)
            continue;
        cout << 1 << endl << a << ' ' << b << endl << s << endl,
        cout << "Output: " << output << endl,
        cout << "Expected: " << correct << endl;
        return 0; }
    cout << "Passed!";
    return 0; }