#include <iostream>
#include <array>
#include <vector>
#include <queue>
#include <algorithm>

using namespace std;

typedef long long ll;
//#define int long long
const int inf = 0x3f3f3f3f;

void solve() {
    int n, m, k;
    cin >> n >> m >> k;
    string s;
    cin >> s;
    s = " " + s;
    vector<int> pre(n + 1);
    for (int i = 1; i <= n; ++i) {
        pre[i] = pre[i - 1] + (s[i] == '1');
    }

    auto check = [&](int x) -> bool {
        vector<vector<array<int, 2>>> dp(n + 1, vector<array<int, 2>>(k + 1, {inf, inf}));
        for(int i=0;i<=n;i++) {
            dp[i][0][0]=0;
        }
        for (int i = 1; i <= n; ++i) {
            for (int j = 0; j <= k; ++j) {
                if(s[i]=='1')
                    dp[i][j][1] = dp[i - 1][j][1];
                else {
                    dp[i][j][0]=min(dp[i-1][j][1],dp[i-1][j][0]);
                    dp[i][j][1]=dp[i-1][j][1]+1;
                }
//                dp[i][j][1] = dp[i - 1][j][1];
                if (i >= x && j >= 1)
                    dp[i][j][1] = min(dp[i][j][1], dp[i - x][j - 1][0] + x - (pre[i] - pre[i - x]));
            }
        }

//        cout << "mid: " << x << endl;
//        for (int i = 1; i <= n; ++i) {
//            for (int j = 0; j <= k; ++j) {
//                cout << "i, j: " << i << ',' << j << ": " << dp[i][j][0] << ' ' << dp[i][j][1] << endl;
//            }
//        }
//        cout << endl;

        return min(dp[n][k][0], dp[n][k][1]) <= m;
    };

    int l = 0, r = n + 1;
    while (l + 1 < r) {
        int mid = l + (r - l) / 2;
        if (check(mid))
            l = mid;
        else
            r = mid;
    }
    cout << (l?l:-1) << '\n';
}

signed main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    cout.tie(nullptr);
    int t = 1;
//    cin >> t;
    while (t--) {
        solve();
    }
    return 0;
}