#include <bits/stdc++.h>

using namespace std;
//#define int long long
using ll = long long;
using ull = unsigned long long;
using pii = pair<int, int>;
const int MAXX = 2e5 + 5;
const int inf = 1e9 + 7;
int s[MAXX];
int sum[MAXX];
int n,m,k;
int dp[MAXX][6][2];
int val(int l,int r){
    return (r - l + 1) - (sum[r] - sum[l - 1]);
}
bool check(int x){
    if(x * k >= n)return false;
    for(int i = 0;i <= n;i++){
        for(int j = 1;j <= k;j++){
            for(int p = 0;p < 2;p++){
                dp[i][j][p] = inf;
            }
        }
    }
    dp[0][0][0] = 0;
    for(int i = 1;i <= n;i++){
        for(int j = 1;j <= k;j++){
            dp[i][j][0] = min(dp[i][j][0],dp[i - 1][j][0]);
            dp[i][j][0] = min(dp[i][j][0],dp[i - 1][j][1]);
            if(i >= x){
                dp[i][j][1] = min(dp[i][j][1],dp[i - x][j - 1][0] + val(i - x + 1,i));
            }
        }
    }
    if(min(dp[n][k][0],dp[n][k][1]) <= m)return true;
    return false;
}
void solve() {
    cin >> n >> m >> k;
    for(int i = 1;i <= n;i++){
        char c;
        cin >> c;
        s[i] = c - '0';
        sum[i] = sum[i - 1] + s[i];
    }
    int l = 0,r = n + 1;
    while(l + 1 < r){
        int mid = (l + r) >> 1;
        if(check(mid)){
            l = mid;
        }else{
            r = mid;
        }
    }
    if(l)cout << l << "\n";
    else cout << -1 << "\n";
}

signed main() {
    ios::sync_with_stdio(false), cin.tie(0);
    int tt = 1;
//    cin >> tt;
    while(tt--){
        solve();
    }
    return 0;
}