#include<bits/stdc++.h>
using namespace std;
#define int long long
#define pii pair<int,int>
#define INF 0x3f3f3f3f3f3f3f3f
#define fi first
#define se second
#define all(_a) _a.begin(),_a.end()
const int N=200010;
int a[N],s[N],last[N];
int n,m,k;
bool check(int x){
    vector<vector<int>> dp(n+2,vector<int>(k+1,INF));
    dp[0][0]=0;
    for(int i=1;i<=n+1;i++){
        dp[i][0]=dp[i-1][0];
        if(a[i]==1)continue;
        for(int j=1;j<=k;j++){
            dp[i][j]=min(dp[i][j],dp[i-1][j]);

            if(i-x-1>=0){
                    //cout<<last[i-x-1]<<" "<<i<<endl;
                dp[i][j]=min(dp[i][j],dp[last[i-x-1]][j-1]+(i-1-last[i-x-1]-(s[i-1]-s[last[i-x-1]])));
            }

        }
    }
    /*
    for(int j=0;j<=k;j++){
        cout<<j<<endl;
        for(int i=1;i<=n;i++)cout<<dp[i][j]<<" ";
        cout<<endl;
    }
    */

    return dp[n+1][k]<=m;
}
void solve(){
    cin>>n>>m>>k;
    for(int i=1;i<=n;i++){
        char x;
        cin>>x;
        a[i]=x-'0';
        s[i]=s[i-1]+a[i];
    }
    s[n+1]=s[n];
    int mx=0;
    for(int i=1;i<=n;i++){
        int j=i;
        while(j+1<=n&&a[j+1]==a[i])j++;
        if(a[i]==1){
            for(int k=i;k<=j;k++)last[k]=i-1;
            i=j;
            mx++;
            continue;
        }
        int len=j-i+1;
        for(int k=i;k<=j;k++)last[k]=k;
        if(i==1&&j==n)mx+=(len+1)/2;
        else if(i==1||j==n)mx+=(len)/2;
        else mx+=(len-1)/2;
        i=j;
    }
    //for(int i=1;i<=n;i++)cout<<last[i]<<" ";
    //cout<<endl;
    if(mx<k){
        cout<<-1<<endl;
        return ;
    }
    //cout<<check(4);

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

    cout<<l;
}

 signed main(){
     ios::sync_with_stdio(false);
     cin.tie(nullptr),cout.tie(nullptr);
     int T=1;
     //cin>>T;
     while(T--) solve();
 }
/*
8 3 2
10110110
3

12 3 3
100100010011
2
4 4 4
0000
-1

*/