#include <bits/stdc++.h>

#define rep(i, x, y) for (int i = x; i <= y; i++)
using namespace std;
const int N = 2e5 + 5, inf = 0x3f3f3f3f;
int n, m, k;
string s;
int dp[N][8][2];

int main() {
    ios::sync_with_stdio(false);
    cin.tie(0);
    cin >> n >> m >> k;
    cin >> s;
    vector<int> pre(n + 1);
    pre[0] = 0;
    rep(i, 1, n) pre[i] = pre[i - 1] + (s[i - 1] == '0');


    auto check = [&](int x) {
        if (x == 0) return true;
        rep(i, 0, n) rep(j, 0, k) dp[i][j][0] = dp[i][j][1] = inf;
        dp[0][0][0] = 0;
        rep(i, 1, n) rep(j, 0, k) {
            if (s[i] == '0') {
                dp[i][j][0] = min({dp[i][j][0], dp[i - 1][j][0], dp[i - 1][j][1]});
                dp[i][j][1] = min(dp[i][j][1], dp[i - 1][j][1] + 1);
            } else {
                dp[i][j][0] = min(dp[i][j][0], dp[i - 1][j][0]);
                dp[i][j][1] = min(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] + pre[i] - pre[i - x]);
        }
        return min(dp[n][k][0], dp[n][k][1]) <= m;
    };

    int l = 0, r = 2e5;
    while (l < r) {
        int mid = (l + r + 1) >> 1;
        if (check(mid)) l = mid;
        else r = mid - 1;
    }
    if (l) cout << l;
    else cout << "-1";
    return 0;
}