#include <iostream>
#include <fstream>
#define Nmax 1048577

using namespace std;

struct Coada
{
    int q[Nmax],pr,ul;void Init(){pr = 0;ul = - 1;}int Empty(){if(pr <= ul) return 0;return 1;}void Push(int x){ul++;q[ul] = x;}void Pop(){if(!Empty()) pr++;}int Front(){return q[pr];}int Size(){return ul - pr + 1;}
};\

int n, nrFinal, v[Nmax];

void Operatie(int &x, int k)
{
    int i, p, z;
    for(p = k; p <= n; p = p + k)
    {
        z = (1 << (p-1)); /// x = 2 la puterea p-1
        x = x ^ z;
    }
}

int main()
{
    int i, doila_i, x, y;
    Coada c, op;
    c.Init(); op.Init();

    ifstream fin("sir.in");
    fin >> n;
    nrFinal = 0;
    doila_i = 1;
    for(i = 0; i < n; i++)
    {
        fin >> x;
        if(x == 1)
            nrFinal += doila_i;
        doila_i *= 2;
    }
    fin.close();

    ///--Initializarea cozii--
    c.Init();
    c.Push(0);
    v[0] = 1;
    op.Push(0);
    int gata = 0;
    while(!c.Empty() && !gata)
    {
        x = c.Front();
        c.Pop();
        for(i = 1; i <= n; i++)
        {
            y = x;
            Operatie(y, i);
            if(v[y] == 0)
            {
                c.Push(y);
                op.Push(i);
                v[y] == 1;
            }
            if(y == nrFinal) gata = 1;
        }
    }

    return 0;
}