$#doanthevu$

#include <bits/stdc++.h>
#define ll long long
using namespace std;
int main() {
    ll n, k;
    ll p;
    cin >> n >> k >> p;
    ll khach[n];
    for (ll i = 0; i < n; i++) {
        cin >> khach[i];
    }
    ll tongtien = 0;
    ll heobit = 0;
    for (ll i = 0; i < n; i += k) {
        long long nhom = 0;
        for (ll j = i; j < min(i + k, n); j++) {
            nhom += khach[j];
        }
        if (nhom >= p) {
            heobit += 20000;
        }
        tongtien += nhom;
    }
    
    cout << heobit << endl;

    return 0;
}