#include <bits/stdc++.h>

const int N = 200100;
const int inf = 0x3f3f3f3f;

int n, m, k;

char str[N];
int a[N], pre[N];

int le[N];
bool is_rg[N];

int f[N][6];

bool check(int mid) {
    for (int i = 0; i <= n; i ++)
        for (int j = 1; j <= k; j ++) f[i][j] = inf;

    for (int i = mid; i <= n; i ++) {
        if (a[i] == 1 && !is_rg[i]) continue;

        for (int j = 1; j <= k; j ++) {
            f[i][j] = std::min(f[i][j], f[i - 1][j]);

            int x = i - mid + 1;

            if (a[x] == 1)
                x = le[x];
            else if (a[x - 1] == 1)
                x = le[x - 1];

            if (x == 1) {
                if (j == 1)
                    f[i][j] = std::min(f[i][j], i - pre[i]);
            } else {
                f[i][j] = std::min(f[i][j], f[x - 2][j - 1] + (i - x + 1) - (pre[i] - pre[x - 1]));
            }
        }
    }

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

int main() {
    scanf("%d%d%d", &n, &m, &k);

    scanf("%s", str + 1);
    for (int i = 1; i <= n; i ++) a[i] = str[i] - '0';

    for (int i = 1; i <= n; i ++) pre[i] = pre[i - 1] + a[i];

    int st = 1, ed;
    while (1) {
        while (a[st] == 0 && st <= n) st ++;

        if (st == n + 1) break;

        for (ed = st;; ed ++)
            if (ed == n || a[ed + 1] == 0) break;

        for (int i = st; i <= ed; i ++) le[i] = st;
        is_rg[ed] = 1;

        if (ed == n) break;

        st = ed + 1;
    }

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

    printf("%d\n", l ? l : -1);

    return 0;
}