#include<iostream>
#include<cstdio>
#include<algorithm>
#include<vector>
#include<queue>
using namespace std;
typedef pair<int,int> PII;
const int inf=0x3fffffff;
const int MX=300030;

int N, M, K;
PII g[MX]; //first:cost, second:end
int f[MX][6], h[MX][6];
int nxt[MX], pre[MX];
int read()
{
    int r=0, f=1; char ch=getchar();
    while(ch<'0'||ch>'9') {if(ch=='-') f=-1; ch=getchar();}
    while(ch>='0'&&ch<='9') {r=r*10+ch-'0'; ch=getchar();}
    return r*f;
}
int main()
{
    // freopen("testdata.in","r",stdin);
    N=read(); M=read(); K=read();
    string s; cin >> s; s=" "+s;
    for(int i=N,p=0;i>=1;i--)
    {
        if(s[i]=='1'&&!p) p=s[i];
        if(s[i]=='1'&&p) nxt[i]=p;
        if(s[i]=='0') p=0;
    }
    for(int i=1;i<=N;i++) pre[i]=pre[i-1]+(s[i]=='0');
    int l=1, r=N, ans=-1;
    while(l<=r)
    {
        int len=(l+r)>>1;
        for(int i=0;i<=N;i++)
            for(int k=1;k<=5;k++)
                f[i][k]=h[i][k]=inf;
        // cout << "len=" << len << '\n';
        for(int i=1;i<=N-len+1;i++)
        {
            for(int k=1;k<=K;k++)
            {
                // h[i][k]=min(f[i][k],h[i-1][k]);
                if(s[i-1]=='1') continue;
                // for(int s=0;s<=max(0,i-1-len);s++)
                // {
                //     f[i][k]=min(f[i][k],f[s][k-1]+pre[i+len-1]-pre[i-1]);
                // }
                f[i][k]=min(f[i][k],h[max(0,i-1-len)][k-1]+pre[i+len-1]-pre[i-1]);
                // cout << "   i=" << i << ", k=" << k << ", f=" << f[i][k] << '\n';
               
            }
            for(int k=1;k<=K;k++) h[i][k]=min(f[i][k],h[i-1][k]);
        }
        int nd=inf;
        for(int i=1;i<=N-len+1;i++)
            nd=min(nd,f[i][K]);
        if(nd<=M) ans=len, l=len+1;
        else r=len-1;
    }
    cout << ans << '\n';
    return (0-0);
}