#include <bits/stdc++.h>
using namespace std;
#define int long long
#define N 200005
#define endl '\n'
int n, m, k, pre[N], dp[N][10][2] = {0};
string s;
bool check(int x)
{
    memset(dp, 0x3f, sizeof(dp));
    dp[0][0][0] = 0;
    dp[0][0][1] = 0;
    for (int i = x; i <= n; i++)
    {
        for (int j = 1; j <= k; j++)
            dp[i][j][1] = dp[i - x][j - 1][0] + pre[i] - pre[i - x];
        for (int j = 0; j <= k; j++)
            dp[i][j][0] = min(dp[i - 1][j][0], dp[i - 1][j][1]);
    }
    return dp[n][k][1] <= m;
}
signed main()
{
    cin >> n >> m >> k;
    cin >> s;
    s = "#" + s;
    for (int i = 1; s[i]; i++)
        pre[i] = pre[i - 1] + (s[i] == '0');
    int l = 0, r = n, ans = 0;
    while (l <= r)
    {
        int mid = (l + r) >> 1;
        if (check(mid))
        {
            ans = mid;
            l = mid + 1;
        }
        else
            r = mid - 1;
    }
    if (ans)
        cout << ans;
    else
        cout << -1;
    return 0;
}