#include <bits/stdc++.h>

#define ios std::ios::sync_with_stdio(0), std::cin.tie(0)
#define int long long

using namespace std;
using pii = pair<int, int>;

const int N = 2e5 + 5;
int n, m, k, dp[N][10], pre[N];
string s;

bool check(int x) {
    vector<pii> es;
    int zeros = 0;
    for (int i = 1; i <= x; i++) {
        if (s[i] == '0') { zeros++; }
    }
    es.push_back({x, zeros});
    for (int i = 2; i <= n - x + 1; i++) {
        int j = i + x - 1;
        if (s[i - 1] == '0') zeros--;
        if (s[j] == '0') zeros++;
        es.push_back({j, zeros});
    }

    memset(dp, 0x3f, sizeof dp);
    dp[0][0] = 0;
    for (auto &[r, w] : es) {
        int l = r - x + 1;
        for (int j = 1; j <= k; j++) {
            dp[r][j] = min(dp[r][j], dp[pre[l]][j - 1] + w);
        }
        for (int j = 1; j <= k; j++) { dp[r][j] = min(dp[r - 1][j], dp[r][j]); }
    }
    return dp[n][k] <= m;
}

void solve() {
    cin >> n >> m >> k;
    cin >> s;
    s = ' ' + s;
    int last = 0;
    for (int i = 1; i <= n; i++) {
        pre[i] = last;
        if (s[i] == '0') last = i - 1;
    }
    int l = 1, r = n;
    // check(3);
    while (l < r) {
        int m = (l + r + 1) >> 1;
        if (check(m)) l = m;
        else r = m - 1;
    }
    if (check(l)) cout << l << "\n";
    else cout << "-1\n";
}

signed main() {
    ios;
    int T = 1;
    while (T--) solve();
    return 0;
}