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#include <bits/stdc++.h>
using namespace std;
int main()
{
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    int n,k,t;
    char x;
    cin>>n>>k>>t;
    vector<int> pre,pre2;
    pre.push_back(0);
    pre2.push_back(0);
    for(int i=1;i<=n;i++)
    {
        cin>>x;
        int curr=int(x)-48;
        if(curr==2)
        {
            pre.push_back(pre[i-1]+1);
            pre2.push_back(pre2[i-1]);
        }
        else if(curr==1)
        {
            pre.push_back(pre[i-1]);
            pre2.push_back(pre2[i-1]+1);
        }
        else
        {
            pre.push_back(pre[i-1]);
            pre2.push_back(pre2[i-1]);
        }
    }
    if(pre2[n]<=k)
    {
        cout<<n-max(0,(pre[n]-k+pre2[n]));
        return 0;
    }
    int ma=-1;
    for(int i=t+1;i<=n-t;i++)
    {
        for(int j=i;j<=n-t;j++)
        {
           int val=pre2[i-1]+pre2[n]-pre2[j]+pre[i-1]-pre[i-t-1]+pre[j+t]-pre[j];
           if(val>k) continue;
           int val2=pre[i-t-1]+pre[n]-pre[j+t];
           ma=max(ma,i-t-1+n-j-t-max(0,(val2-k+val)));

        }
    }
    cout<<ma;
}