#include <bits/stdc++.h>
//#pragma GCC optimize("Ofast")
//#pragma GCC target("avx,avx2,fma")
using namespace std;
#define sped_up ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
#define ll long long
const ll INF = (ll)1e9 + 1, INFL = (ll)1e18 + 1;
const ll mod = (ll)1e9 + 7, MAXN = (ll)301;
ll a[MAXN];
ll b[MAXN];
int main () {
sped_up;
ll n, m, k;
ll sum = 0;
cin >> n >> m >> k;
for (int i = 1; i <= n; i++) cin >> a[i];
for (int i = 1; i <= m; i++) cin >> b[i];
for (int i = 1; i <= n; i++) {
ll mn = INFL;
for (int mask = 0; mask < (1 << m); mask++) {
ll cnt = 0;
for (int j = 1; j <= m; j++) {
if (((mask >> (j - 1)) & 1) == 1) {
cnt += b[j];
}
}
if (__builtin_popcount(mask) >= k && cnt >= a[i] && a[i] >= __builtin_popcount(mask)) {
mn = min(mn, cnt);
}
}
if (mn == INFL) {
cout << "Impossible";
return 0;
}
sum += mn - a[i];
}
cout << sum;
}
