#include <bits/stdc++.h>
using namespace std;
const int N = 2e5 + 10;

int n, m, k, S[N], a[N], dp[N][6], mn[N][6], lp[N];

void ckmn(int &x, int y) {
    if (x > y)
        x = y;
}

bool check(int len) {
    memset(dp, 0x3f, sizeof dp);
    memset(mn, 0x3f, sizeof mn);
    for (int i = 1; i <= n; i++)
        if (i >= len) {
            dp[i][1] = S[i] - S[i - len];
            mn[i][1] = min(mn[i - 1][1], dp[i][1]);
        }
    for (int i = 1; i <= n; i++)
        for (int j = 2; j <= k; j++) {
            if (i >= len + 1) {
                int p = lp[i - len];
                if (p > 0)
                    ckmn(dp[i][j], mn[p - 1][j - 1] + S[i] - S[p]);
            }
            mn[i][j] = mn[i - 1][j]; //？？？？
            ckmn(mn[i][j], dp[i][j]); // ？？？？
        }

    return mn[n][k] <= m;
}

int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);

    cin >> n >> m >> k;

    string s;
    cin >> s;

    int pos = 0;
    for (int i = 1; i <= n; i++) {
        int x = s[i - 1] - '0';
        a[i] = x;
        S[i] = S[i - 1] + (a[i] == 0);
        if (!a[i])
            pos = i;
        lp[i] = pos;
    }


    int l = 0, r = n;
    while (l + 1 < r) {
        int mid = l + r >> 1;
        if (check(mid))
            l = mid;
        else
            r = mid;
    }

    if (check(l))
        cout << l;
    else 
        cout << -1;
}