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#include <bits/stdc++.h>
#define LL long long
#define endl '\n'
using namespace std;
vector<int> prefpra,sufpra,prefzda,sufzda;
int main()
{
    std::ios_base::sync_with_stdio(0);  
    cout.tie(0);
    cin.tie(0);

    int n,k,t,ans=-1,pra=0,zda=0; cin>>n>>k>>t;
    string s; cin>>s;
    for(int i=0;i<n;i++)
    if(s[i]=='1') pra++;
    else if(s[i]=='2') zda++;
    if(pra<=k) cout<<min(n,n-zda-pra+k);
    else{
        int musze=pra+zda-k;
        prefpra.resize(n+1);
        sufpra.resize(n+1);
        prefzda.resize(n+1);
        sufzda.resize(n+1);
        if(s[0]=='1') prefpra[0]=1;
        else if(s[0]=='2') prefzda[0]=1;
        for(int i=1;i<n;i++) {
            prefpra[i]=prefpra[i-1]+(int)(s[i]=='1');
            prefzda[i]=prefzda[i-1]+(int)(s[i]=='2');
        }
        if(s[n-1]=='1') sufpra[n-1]=1;
        else if(s[n-1]=='2') sufzda[n-1]=1;
        for(int i=n-2;i>=0;i--) {
            sufpra[i]=sufpra[i+1]+(int)(s[i]=='1');
            sufzda[i]=sufzda[i+1]+(int)(s[i]=='2');
        }

        for(int i=t;i<n;i++){
            for(int j=i;j<n-t;j++){
                int skip=prefpra[i-1]+sufpra[j+1]+(prefzda[i-1]-prefzda[i-t-1])+(sufzda[j+1]-sufzda[j+t+1]);
                //cout<<i<<" "<<j<<" "<<skip<<endl;
                //int w=n-pra-zda;
                if(skip<=k) ans=max(ans,n-(j-i+1+2*t)-max(musze-(prefpra[j]-prefpra[i-1])-(prefzda[j]-prefzda[i-1]),0));
            }
        }
        cout<<ans;
    }
}