#include <bits/stdc++.h>
using namespace std;
#define inf 0x3f3f3f3f3f3f3f3f
#define pb push_back
#define int long long
const int mod = 1e9 + 7;
const int N = 1e6 + 50;
int x[N];
void solve()
{
    int n, k;
    cin >> n >> k;
    for (int i = 0; i < n; i++)
    {
        cin >> x[i];
    }
    string s;
    cin >> s;
    int min1 = 10000000000, min2 = 0;
    int num = 0;
    for (int i = 0; i < n - 1; i++)
    {
        if (s[i] == '1' && s[i + 1] == '1')
        {
            if (num == 0)
            {
                num = 2;
            }
            else
            {
                num++;
            }
            min1 = min(min1, x[i]);
            min1 = min(min1, x[i + 1]);
        }
        else
        {
            if (num >= k)
            {
                min2 = max(min2, min1);
                min1 = 10000000000;
                num = 0;
            }
        }
    }
    cout << min2;
}
signed main()
{
    ios::sync_with_stdio(false), cin.tie(0), cout.tie(0);
    int T = 1;
    // cin >> T;
    while (T--)
    {
        solve();
    }
}