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// clang-format off
#include<bits/stdc++.h>
using namespace std;
#define ll long long
#define ssize(x) int(x.size())
template<class A,class B>auto&operator<<(ostream&o,pair<A,B>p){return o<<'('<<p.first<<", "<<p.second<<')';}
template<typename T,typename = typename enable_if<!is_same<T,string>::value>::type>
auto operator<<(ostream&o,T x)->decltype(x.end(),o){o<<'{';int i=0;for(auto e:x)o<<(", ")+2*!i++<<e;return o<<'}';}
#ifdef DEBUG
#define debug(x...) cerr<<"["#x"]: ",[](auto...$){((cerr<<$<<"; "),...);}(x),cerr<<'\n'
#else
#define debug(...) {}
#endif
// clang-format on

int prefsum[8008][3];

int main()
{
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);

    int n, k, t;
    cin >> n >> k >> t;
    string s;
    cin >> s;
    for (int i = 1; i <= n; i++)
    {
        for (int j = 0; j < 3; j++)
        {
            prefsum[i][j] = prefsum[i - 1][j];
        }
        prefsum[i][s[i - 1] - '1']++;
    }

    int ans = -1;
    int skipped, res;
    if (prefsum[n][0] <= k)
    {
        cout << min(n, prefsum[n][2] + k) << '\n';
        return 0;
    }

    for (int st = 1; st <= n - t * 2 + 1; st++)
    {
        for (int en = st + t * 2 - 1; en <= n; en++)
        {
            skipped = prefsum[st + t - 1][0];
            skipped += prefsum[st + t - 1][1] - prefsum[st - 1][1];
            skipped += prefsum[n][0] - prefsum[en - t][0];
            skipped += prefsum[en][1] - prefsum[en - t][1];
            if (skipped > k)
                continue;
            res = prefsum[st - 1][2] + prefsum[n][2] - prefsum[en][2];
            res += prefsum[st - 1][0] + prefsum[n][0] - prefsum[en][0];
            res += min(k - skipped, prefsum[st - 1][1] + prefsum[n][1] - prefsum[en][1]);
            ans = max(ans, res);
        }
    }

    cout << ans << '\n';

    return 0;
}