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#include <bits/stdc++.h>
using namespace std;
#define rep(i, n) for(int i= 0; i<(n); i++)
#define reps(i,s, n) for(int i= (s); i<(n); i++)
#define each(a, x) for (auto &a : x)
#define vv(T) vector<T>
#define endl '\n'
#define sz(x) (int)x.size()
#define ll long long
#define all(c) begin(c), end(c)
#define fi first
#define se second
#define mp make_pair
#define pb push_back
#define pd pair<int,int> 
#define wr cout<<
#define wre wr endl;
#define wrut(a) {each(i,(a))wr i<<" "; wre}
#define wrot(a,b,c) {wre wr a<<" "<<b<<" "<<c<<" ";wre}
// #define int ll
// const int inf =1e9+7;
// bool comp(pd p1,pd p2){
//     return p1.se>p2.se;
// }
signed main() {
    ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
    int n,k,t;
    cin>>n>>k>>t;
    // k=n-k;
    string x;
    cin>>x;
    int s;
    vv(int) pref2(n+1,0),suf2(n+1,0),pref(n+1,0);
    rep(i,n){
        pref2[i+1]=pref2[i];
        pref[i+1]=pref[i];
        if(x[i]=='2')pref2[i+1]++;
        if(x[i]=='1')pref[i+1]++;
    }
    rep(i,n){
        suf2[n-i-1]=suf2[n-i];
        if(x[n-i-1]=='2')suf2[n-i-1]++;
    }
    s=pref[n]+pref2[n];
    if(s<=k){
        wr n;
        return 0;
    } else if(pref[n]<=k){
        wr n-s+k;
        return 0;
    }
    int m=-1;
    rep(i,n-t){
        reps(j,i+2*t,n){
            // wrot(i,j,s-(pref2[i]+suf2[j+1]+pref[j-t+1]-pref[i+t]+pref2[j-t+1]-pref2[i+t]));
            if(s-(pref2[i]+suf2[j+1]+pref[j-t+1]-pref[i+t]+pref2[j-t+1]-pref2[i+t])<=k){
                // wrot(i,j,-1);
                m=max(m,k-(s-(pref2[i]+suf2[j+1]+pref[j-t+1]-pref[i+t]+pref2[j-t+1]-pref2[i+t]))+i-pref2[i]+n-j-1-suf2[j+1]);
            }
        }
    }
    wr m;
}