#include<iostream>
#include<cstring>
#include<vector>
using namespace std;
using LL = long long;

int main(){

#ifdef LOCAL
    freopen("data.in", "r", stdin);
    freopen("data.out", "w", stdout);
#endif

    cin.tie(0);
    cout.tie(0);
    ios::sync_with_stdio(0);

    const int INF = 1e9;
    int n, m, k;
    cin >> n >> m >> k;
    string s;
    cin >> s;
    s = " " + s;
    vector<int> pre(n + 1), last(n + 1);
    for(int i = 1; i <= n; i++){
        last[i] = last[i - 1];
        if (s[i - 1] == '0') last[i] = i - 1;
        pre[i] = pre[i - 1] + (s[i] == '0');
    }

    auto check = [&](int mid){
        vector<vector<int> > dp(n + 1, vector<int>(k + 1, INF));
        dp[0][0] = 0;
        for(int i = 1; i <= n; i++){
            dp[i] = dp[i - 1];
            if (i == n || (s[i + 1] == '0')){
                if (i - mid + 1 >= 1){
                    int t = last[i - mid + 1];
                    if (t >= 1) t -= 1;
                    int cnt = pre[i] - pre[i - mid];
                    for(int j = 0; j < k; j++){
                        dp[i][j + 1] = min(dp[i][j + 1], dp[t][j] + cnt);
                    }
                }
            }
        }
        return dp[n][k] <= m;
    };

    int l = 0, r = n;
    while(l < r){
        int mid = (l + r + 1) / 2;
        if (check(mid)) l = mid;
        else r = mid - 1;
    }
    if (r == 0) r = -1;
    cout << r << '\n';

}