#include <queue>
#include <cstdio>
#include <vector>
#include <cstring>

using namespace std;

int W;
struct Edge {
    int u;
    int v;
    int w;
} G[209];
struct Ed {
    int v;
    int w;
};
vector<Ed> E[69];
int N;
char s[209];
bool A[209];
queue<int> q;
bool in[69];
int dis[69];

bool Chk () {
    int t;
    while (!q.empty()) q.pop();
    memset(in, 0, sizeof(in));
    memset(dis, 0x3f, sizeof(dis));
    dis[0] = 0, q.push(0);
    in[0] = true;
    while (!q.empty()) {
        t = q.front(), q.pop();
        in[t] = false;
        for (Ed v : E[t])
            if (dis[v.v] > dis[t] + v.w) {
                dis[v.v] = dis[t] + v.w;
                if (!in[v.v]) q.push(v.v), in[v.v] = true;
            }
        if (dis[0] < 0) return false;
    }
    return true;
}

int main () {
    scanf("%d%s", &W, s);
    N = (1 << (2 * W + 1));
    for (int i = 0; i < N; i++) A[i] = s[i] - '0';
    for (int i = 0; i < (1 << (2 * W)); i++) G[i] = {i, i >> 1, 0}, G[(i | (1 << (2 * W)))] = {i, (i | (1 << (2 * W))) >> 1, 1};
    for (int i = N; i >= 0; i--)
        if (!A[i]) {
            A[i] ^= 1;
            for (int j = 0; j < (1 << (2 * W)); j++) E[j].clear();
            for (int j = 0; j < N; j++)
                if (j <= i) E[G[j].u].push_back({G[j].v, G[j].w - A[j]}), E[G[j].v].push_back({G[j].u, A[j] - G[j].w});
                else E[G[j].u].push_back({G[j].v, G[j].w}), E[G[j].v].push_back({G[j].u, G[j].w ^ 1});
            if (Chk()) {
                for (int j = 0; j <= i && j < N; j++) putchar(A[j] + '0');
                for (int a = i + 1; a < N; a++) {
                    for (int b = 0; b < (1 << (2 * W)); b++) E[b].clear();
                    A[a] = 0;
                    for (int j = 0; j < N; j++)
                        if (j <= a) E[G[j].u].push_back({G[j].v, G[j].w - A[j]}), E[G[j].v].push_back({G[j].u, A[j] - G[j].w});
                        else E[G[j].u].push_back({G[j].v, G[j].w}), E[G[j].v].push_back({G[j].u, G[j].w ^ 1});
                    if (Chk()) putchar('0');
                    else A[a] = 1, putchar('1');
                }
                puts("");
                return 0;
            }
            A[i] ^= 1;
        }
    puts("no");
    return 0;
}