//
// Created by wind on 24-10-13.
//

#include <bits/stdc++.h>

using namespace std;

using ll = long long;

void solve() {

}
string s;
const int N = 2e5 + 10;
int n,m,k;
int dp[N][6][2];
int pre[N];
int sum[N];
int check(int mid){
    for(int i = 0 ; i <= n ; i++){
        for(int j = 0 ; j <= k ; j++){
            dp[i][j][1] = 1e9;
            dp[i][j][0] = 1e9;
        }
    }
    dp[0][0][0] = 0;
    for(int i = 1 ; i <= n ; i++){
        for(int j = 0 ; j <= k ; j++){
            if(s[i] == '1'){
                dp[i][j][0] = 1e9;
                dp[i][j][1] = dp[i - 1][j][1];
                int pos = i - mid;
                if(pos < 0) continue;
                pos = pre[pos];
                dp[i][j][1] = min(dp[i][j][1] , dp[pos][j - 1][0] + sum[i] - sum[pos]);

            }else{
                dp[i][j][0] = min({dp[i - 1][j][0], dp[i - 1][j][1]});
                dp[i][j][1] = dp[i - 1][j][1];
                int pos = i - mid;
                if(pos < 0) continue;
                pos = pre[pos];
                dp[i][j][1] = min(dp[i][j][1] , dp[pos][j - 1][0] + sum[i] - sum[pos]);
            }



        }
        //cout<<endl;
    }

    return (min(dp[n][k][1] , dp[n][k][0]) <= m);
}

int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    cin>>n>>m>>k;
    cin>>s;
    s = "0" + s;
    sum[1] = 1;
    for(int i = 1 ; i <= n ; i++){
        pre[i] = pre[i - 1];
        if(s[i] == '0') pre[i] = i;
        sum[i] = sum[i - 1] + (s[i] == '0') ;
    }
    int left = 1 , right = 1e6;
    while(left < right){
        int mid = (left + right + 1) >> 1;
        if(check(mid)) left = mid;
        else right = mid - 1;
    }
    
    
    
    if(!check(left)) left = -1;
    cout<<left<<"\n";



    return 0;
}