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/*
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Ǫ╫lj−ф╫╫╫╟ҨɊû[яҦ╫▓▓▓▓▓▓█████▓▓ƥ~«Ҩ╬∆ύȜύчȘ

Matthew's cool cp template
*/
#include <bits/stdc++.h>
using namespace std;
#define int long long

#pragma GCC optimize("Ofast")
#pragma GCC target("avx,avx2,fma")
#pragma GCC optimize("unroll-loops")
#pragma GCC optimize("O3")

template<typename T>
ostream& operator<<(ostream& os, vector<T>& v){
    os << "{";
    for(int i = 0; i+1 < v.size(); i++)
        os << v[i] << ", ";
    v.empty()?
        os << "}":
        os << v.back() << "}";
    return os;
}
template<typename T>
istream& operator>>(istream& is, vector<T>& v){
    T c0;
    is >> c0;
    v.push_back(c0);
    return is;
}

int x1[8001];
int x2[8001];
int l1[8001];
int l2[8001];
int PD[8001];

signed main(){
    bool debug = false;
    int n, k, t;
    cin >> n >> k >> t;
    string s;
    cin >> s;

    int Pc=0;
    int Dc=0;
    int nc=0;
    x1[0] = 0;
    x2[s.size()] = 0;
    l1[0] = 0;
    l2[s.size()] = 0;
    PD[0] = 0;
    for(int i = 0; i < s.size(); i++){
        if(s[i]=='1'){
            Pc++;
        }
        else if(s[i]=='2'){
            Dc++;
        }
        else if(s[i]=='3'){
            nc++;
        }
        x1[i+1] = Dc;
        l1[i+1] = nc;
        PD[i+1] = Pc+Dc;
    }
    Pc=0;
    Dc=0;
    nc=0;
    for(int i = s.size()-1; i >= 0; i--){
        if(s[i]=='1'){
            Pc++;
        }
        else if(s[i]=='2'){
            Dc++;
        }
        else if(s[i]=='3'){
            nc++;
        }
        x2[i] = Dc;
        l2[i] = nc;
    }
    int nk = Pc+Dc-k;
    if(debug){
        for(int i = 0; i < n; i++){
            cout << x1[i] << " ";
        }
        cout << "\n";
        
        for(int i = 0; i < n; i++){
            cout << x2[i] << " ";
        }
        cout << "\n";
        
        for(int i = 0; i < n; i++){
            cout << l1[i] << " ";
        }
        cout << "\n";
        
        for(int i = 0; i < n; i++){
            cout << l2[i] << " ";
        }
        cout << "\n";
        
        for(int i = 0; i < n; i++){
            cout << PD[i] << " ";
        }
        cout << "\n";
        cout << nk << "\n";
    }
    int pb = INT_MIN;
    if(x2[0]>=nk)pb=n-max(nk,(int)0);

    register int r0, r1;
    for(int l = 0; l <= n-2*t; l++){
        for(int r = l+t+1; r <= n-t; r++){
            r0 = x1[l]+x2[r+t];
            r1 = PD[r]-PD[l+t];
            if(r1<nk){
                if(r0+r1<nk)
                    continue;
                r0 -= nk-r1;
            }
            // pb = max(pb, l1[l-1]+l2[r+t]+r0); //might be slow, to be optimised later
            if(l1[l]+l2[r+t]+r0>pb){
                pb = l1[l]+l2[r+t]+r0;
                // if(debug){
                //     cout << pb << "\n";
                //     cout << l << "\n";
                //     cout << r << "\n";
                //     cout << x1[l]+x2[r+t] << "\n";
                //     cout << PD[r]-PD[l+t] << "\n\n";
                // }
            }
        }
    }
    if(pb<0)cout << "-1\n";
    else    cout << pb << "\n";
}

/*
10 1 2
3233313132


*/