#include <bits/stdc++.h>
using namespace std;
#define int ll

#define pb push_back
#define Mp make_pair
#define SZ(x) (int((x).size()))

typedef long long ll;
typedef pair<int, int> pii;
typedef vector<int> vi;

constexpr int N = 200100;

int n, m, k, sum[N];
string s; vi p0;
bool chk(int lim) {
    vector<vi> f(n + 1, vi(k + 1, 1e9));
    vi g(k + 1, 1e9);
    f[0][0] = 0;
    int t = 0;
    for(int i = 1; i <= n; i++) if(s[i] == '0') {
        while(t < SZ(p0) && i - lim - 1 >= p0[t]) {
            int p = p0[t];
            for(int j = 0; j <= k; j++) {
                g[j] = min(g[j], f[p][j] - sum[p]);
            }
            t++;
        }
        for(int j = 0; j <= k; j++) {
            if(j) f[i][j] = min(f[i][j], g[j - 1] + sum[i - 1]);
            else f[i][j] = 0;
        }
    }
    return f[n][k] <= m;
}
void solve() {
    cin >> n >> m >> k >> s;
    s = '0' + s + '0';
    n++;
    for(int i = 0; i <= n; i++)
        if(s[i] == '0') p0.pb(i);
    sum[0] = 1;
    for(int i = 1; i <= n; i++)
        sum[i] = sum[i - 1] + (s[i] == '0');
    
    chk(3);
    int lo = 1, hi = n, mid;
    while(lo < hi) {
        mid = (lo + hi + 1) / 2;
        if(chk(mid)) lo = mid;
        else hi = mid - 1;
    }
    if(chk(lo)) cout << lo << '\n';
    else cout << "-1\n";
}
signed main() {
    ios::sync_with_stdio(false), cin.tie(0), cout.tie(0);
    int t = 1;
    // cin >> t;
    while(t--) solve();
    return 0;
}