#include <bits/stdc++.h>
using namespace std;
const int INF = 1e9 + 10;
const int MAXN = 312;
vector<int> a, b;
int resp;
int n, m, k, sum_a;
void try_set(int bm) {
vector<int> cur;
for (int i = 0; i < m; i++) {
if (bm & (1 << i)) {
cur.push_back(b[i]);
}
}
int lo = 0;
int cur_r = 0, cur_c = 0;
int sum_b = 0, sum_rect = 0;
for (int x: cur) {
sum_rect += min(x, n);
sum_b += x;
}
// cout << "tested bitmask " << bitset<2>(bm) << endl;
// cout << "sum_rect = " << sum_rect << " sum_b = " << sum_b << endl;
int delta = sum_b - sum_a;
if (sum_rect >= n * k && delta >= 0) {
resp = min(resp, delta);
}
}
void solve() {
resp = INF;
cin >> n >> m >> k;
a.resize(n); b.resize(m);
for (int i = 0; i < n; i++) {
cin >> a[i];
if (a[i] < k) {
cout << "Impossible\n";
return;
}
sum_a += a[i];
}
for (int i = 0; i < m; i++) {
cin >> b[i];
}
int lim = (1LL << m);
for (int bm = 0; bm < lim; bm++) {
try_set(bm);
}
if (resp == INF) {
cout << "Impossible\n";
return;
}
cout << resp << "\n";
}
int32_t main() {
solve();
return 0;
}
