//#pragma clang diagnostic push
//#pragma ide diagnostic ignored "misc-no-recursion"

#include<bits/stdc++.h>

using namespace std;

int v[200005];
int dp[200005];
int n;

inline bool check(int k, int m, int start, int ans) {
    if (ans == 0)return true;
    for (int i = start; i + ans - 1 < n; ++i) {
        if (m >= v[i + ans] - v[i]) {
            if (k == 1)return true;
            if (check(k - 1, m - (v[i + ans] - v[i]), dp[i + ans] + 1, ans))return true;
        }
    }
    return false;
};

int m, k;

inline int find() {
    int l = 0, r = n / k + 1;
    while (l + 1 < r) {
        int mid = (l + r) / 2;
        if (check(k, m, 0, mid)) {
            l = mid;
        } else {
            r = mid;
        }
    }
    return l;
};

int main() {
    cin.tie(nullptr)->sync_with_stdio(false);
    cin >> n >> m >> k;
    string s;
    cin >> s;
    for (int i = 0; i < n; ++i) {
        v[i + 1] = v[i] + (s[i] == '0');
    }
    dp[n] = n;
    for (int i = n - 1; i >= 0; --i) {
        if (s[i] == '0') {
            dp[i] = i;
        } else {
            dp[i] = dp[i + 1];
        }
    }
//    for(int i=0;i<n;++i){
//        cout<<check(check, k, m, 0, i);
//    }
    int ans = find();
    if (ans == 0)ans--;
    cout << ans << endl;
}
//11 11 3
//00000001000

//#pragma clang diagnostic pop