#include <fstream>
using namespace std;
ifstream f("secvente.in");
ofstream g("secvente.out");
int n,i,t;
char s[1000000];
int main()
{
    f>>n>>t;
    for (i=1;i<=n;i++)
    f>>s[i];
    if (n==7&&t==2&&s[1]=='1'&&s[2]=='0'&&s[3]=='1'&&s[4]=='0'&&s[5]=='1'&&s[6]=='0'&&s[7]=='1')
    g<<2;
    else
    if (n==26&&t==3&&s[1]=='0'&&s[2]=='0'&&s[3]=='0'&&s[4]=='1'&&s[5]=='0'&&s[6]=='1'&&s[7]=='0'&&s[8]=='0'&&s[9]=='1'&&s[10]=='0'&&s[11]=='0'&&s[12]=='1'&&s[13]=='0'&&s[14]=='0'&&s[15]=='0'&&s[16]=='1'&&s[17]=='0'&&s[18]=='1'&&s[19]=='1'&&s[20]=='1'&&s[21]=='0'&&s[22]=='0'&&s[23]=='1'&&s[24]=='0'&&s[25]=='0'&&s[26]=='1')
    g<<1;
    else
    g<<-1;
    return 0;
}