#include <bits/stdc++.h>

using namespace std;

#define int long long
#define double long double
using i64 = long long;

typedef pair<int, int> PII;
typedef pair<int, char> PIC;
typedef pair<double, double> PDD;
typedef pair<PII, int> PIII;
typedef pair<int, pair<int, bool>> PIIB;
typedef pair<PII, PII> PIIII;

const int N = 1e5 + 10;
const int maxn = 1e6;
const int MAXN = 100;
const int mod = 998244353;
const int mod1 = 954169327;
const int mod2 = 906097321;
const int INF = 0x3f3f3f3f3f3f3f3f;

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] == '0');
    //dp[i][j][0/1] 表示前 i 个字符中有 j 段长度大于等于 mid 的连续 1 子串且第 i 位为 0/1 的最小操作数
    vector<vector<vector<int>>> dp(n + 1, vector<vector<int>>(k + 1, vector<int>(2, INF)));
    auto check = [&](int x)
    {
        for (int i = 0; i <= n; i++)
        {
            for (int j = 0; j <= k; j++)
            {
                dp[i][j][0] = dp[i][j][1] = INF;
            }
        }
        dp[0][0][0] = dp[0][0][1] = 0;
        for (int i = 1; i <= n; i++)
        {
            for (int j = 0; j <= k; j++)
            {
                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 = n;
    while (l < r)
    {
        int mid = (l + r + 1) >> 1;
        if (check(mid)) l = mid;
        else r = mid - 1;
    }
    if (r > 0) cout << r << '\n';
    else cout << -1 << '\n';
}

signed main()
{
    ios::sync_with_stdio(false);
    cin.tie(0), cout.tie(0);

#ifndef ONLINE_JUDGE
    freopen("in.txt", "rt", stdin);
    freopen("out.txt", "wt", stdout);
#endif

    int t = 1;
    // cin >> t;
    while (t--)
    {
        solve();
    }
    return 0;
}