using namespace std;

unsigned long long n,k,f[40][40][32]={0};

string s;

unsigned long long work(int l,int r,int k)

{

if(f[l][r][k])return f[l][r][k];

if(k)for(int i=l+k/2;i<=r-k/2;i++)f[l][r][k]=max(f[l][r][k],work(l,i,k/2)*work(i+1,r,k-k/2-1));

else for(int i=l;i<=r;i++)f[l][r][k]=f[l][r][k]*10+s[i]-'0';

return f[l][r][k];

}

int main()

{

cin>>n>>k>>s;

cout<<work(0,n-1,k);

}