#include <bits/stdc++.h>

using namespace std;

#define ft first
#define sd second

#define yes cout << "yes\n"
#define no cout << "no\n"

#define Yes cout << "Yes\n"
#define No cout << "No\n"

#define YES cout << "YES\n"
#define NO cout << "NO\n"

#define pb push_back
#define eb emplace_back

#define all(x) x.begin(), x.end()
#define all1(x) x.begin() + 1, x.end()
#define unq_all(x) x.erase(unique(all(x)), x.end())
#define unq_all1(x) x.erase(unique(all1(x)), x.end())
#define inf 0x3f3f3f3f
#define infll 0x3f3f3f3f3f3f3f3fLL

#define RED cout << "\033[91m"     // 红色
#define GREEN cout << "\033[92m"   // 绿色
#define YELLOW cout << "\033[93m"  // 蓝色
#define BLUE cout << "\033[94m"    // 品红
#define MAGENTA cout << "\033[95m" // 青色
#define CYAN cout << "\033[96m"    // 青色
#define RESET cout << "\033[0m"    // 重置

typedef long long ll;
typedef unsigned long long ull;
typedef long double ld;
// typedef __int128_t i128;

typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
typedef pair<ll, int> pli;
typedef pair<string, ll> psl;

typedef tuple<int, int, int> ti3;
typedef tuple<ll, ll, ll> tl3;
typedef tuple<ld, ld, ld> tld3;

typedef vector<bool> vb;
typedef vector<int> vi;
typedef vector<ll> vl;
typedef vector<string> vs;
typedef vector<vi> vvi;
typedef vector<vl> vvl;

// std::mt19937_64 rng(std::chrono::steady_clock::now().time_since_epoch().count());

template <typename T>
inline T read()
{
    T x = 0;
    int y = 1;
    char ch = getchar();
    while (ch > '9' || ch < '0')
    {
        if (ch == '-')
            y = -1;
        ch = getchar();
    }
    while (ch >= '0' && ch <= '9')
    {
        x = (x << 3) + (x << 1) + (ch ^ 48);
        ch = getchar();
    }
    return x * y;
}

template <typename T>
inline void write(T x)
{
    if (x < 0)
    {
        putchar('-');
        x = -x;
    }
    if (x >= 10)
    {
        write(x / 10);
    }
    putchar(x % 10 + '0');
}

/*#####################################BEGIN#####################################*/
void solve()
{
    int n, m, k;
    cin >> n >> m >> k;
    string s;
    cin >> s;
    s = "#" + s;
    vi pre(n + 1);
    for (int i = 1; i <= n; i++)
    {
        pre[i] = pre[i - 1] + (s[i] == '0');
    }
    auto check = [&](int x) -> bool
    {
        vvi f(n + 1, vi(k + 1, inf));
        vvi g(n + 1, vi(k + 1, inf));
        f[0][0] = 0;
        g[0][0] = 0;
        for (int i = 1; i <= n; i++)
        {
            for (int j = 0; j <= k; j++)
            {
                if (s[i] == '0')
                    g[i][j] = min(g[i - 1][j], f[i - 1][j]);
                else
                    f[i][j] = min(g[i - 1][j], f[i - 1][j]);
                if (i >= x && j >= 1)
                    f[i][j] = min(f[i][j], g[i - x][j - 1] + (pre[i] - pre[i - x]));
            }
        }
        return min(g[n][k], f[n][k]) <= m;
    };

    int l = 1, r = n;
    while (l < r)
    {
        int mid = (l + r + 1) >> 1;
        if (check(mid))
            l = mid;
        else
            r = mid - 1;
    }
    if (check(r))
        cout << r << "\n";
    else
        cout << "-1\n";
}

int main()
{
    ios::sync_with_stdio(false), std::cin.tie(0), std::cout.tie(0);
    // freopen("test.in", "r", stdin);
    // freopen("test.out", "w", stdout);
    int _ = 1;
    // std::cin >> _;
    while (_--)
    {
        solve();
    }
    return 0;
}

/*######################################END######################################*/
// 链接：