#include<bits/stdc++.h>
#include<unordered_map>
#define pii pair<int, int>
#define LL long long
#define pll pair<LL, LL>

using namespace std;
typedef long long ll;

LL dp[200015][7];
vector<int> a(200015, 0), nxt(200015, 0);

void solve()
{
    int n, m, k;
    string s;
    cin >> n >> m >> k >> s;
    s = "0" + s + "0";

    for (int i = 1; i <= n; i++)
        a[i] = a[i - 1] + (s[i] == '0');
    nxt[n + 1] = n + 1;
    for (int i = n; i >= 1; i--)
        nxt[i] = (s[i] == '1' ? nxt[i + 1] : i);

    auto check = [&n, &m, &k](int x) -> bool
    {
        for (int i = 0; i <= n + 2; i++)
            dp[i][0] = 0;
        for (int i = 0; i <= n + 2; i++)
            for (int j= 1; j <= k; j++)
                dp[i][j] = 1e9;

        for (int i = 1; i <= n - x + 1; i++)
        {
            for (int j = 0; j < k; j++)
                dp[nxt[i + x] + 1][j + 1] = min(dp[nxt[i + x] + 1][j + 1], dp[i][j] + a[i + x - 1] - a[i - 1]);
            if (dp[i][k] <= m)
                return true;
        }

        return dp[n + 1][k] <= m || dp[n + 2][k] <= m;
    };

    LL l = 0, r = n / k;
    while (l < r)
    {
        LL mid = l + r + 1 >> 1;

        if (check(mid))
            l = mid;
        else
            r = mid - 1;
    }

    cout << (l ? l : -1) << "\n";
}

int main()
{
    ios::sync_with_stdio(0), cin.tie(0), cout.tie(0);

    int tt = 1;
    //cin >> tt;
    while (tt--)
        solve();
}