#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<int, int> pii;
const int N = 1e6 + 7;
#define lc p << 1
#define rc p << 1 | 1
ll a[N], pre[N], f[N][6][2];
ll n, m, k;
bool check(int x)
{
    for (int i = 0; i <= n; i++)
        for (int j = 0; j <= k; j++)
            f[i][j][1] = f[i][j][0] = 1e9;
    ll ans = 2e9;
    f[0][0][0] = 0;
    for (int i = 1; i <= n; i++)
    {
        for (int j = 0; j <= k; j++)
        {
            if (i >= x && j)
            {
                // cout << i << ' ' << (f[i - x][j - 1][0]) << '\n';
                f[i][j][1] = min(f[i][j][1], f[i - x][j - 1][0] + x - (pre[i] - pre[max(0, i - x)]));
                if (j == k)
                    ans = min(ans, f[i][j][1]);
            }
            f[i][j][0] = min(f[i - 1][j][0], f[i - 1][j][1]);
        }
    }
    return ans <= m;
}
void slove()
{
    cin >> n >> m >> k;
    string s;
    cin >> s;
    vector<int> p;
    s = "!" + s;
    pre[0] = 0;
    for (int i = 1; i <= n; i++)
    {
        pre[i] = pre[i - 1] + (s[i] == '1');
    }
    int l = 1;
    int r = n;
    while (l != r)
    {
        int mid = l + r >> 1;
        if (check(mid))
        {
            l = mid + 1;
        }
        else
        {
            r = mid;
        }
    }
    if (!check(l))
        l--;
    if (!check(1))
        l = -1;
    cout << l << '\n';
}
int main()
{
    // cout << fixed << setprecision(10);
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);
    // int t;
    // cin>>t;
    // while(t--)
    slove();
}