//#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,tune=native")
//#pragma GCC optimize("Ofast,unroll-loops,fast-math,O3")
#include<bits/stdc++.h>
using namespace std;
#define all(a) a.begin(), a.end()
#define rall(a) a.rbegin(), a.rend()
#define sz(a) (int)a.size()
#define s second
#define f first
using ll = long long;
using pii = pair<int, int>;
using pll = pair<ll, ll>;
mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count());
vector<pii> rid = {{0, 1}, {0, -1}, {1, 0}, {-1, 0}};
vector<pii> dir = {{-1, -1}, {-1, 1}, {1, -1}, {1, 1}};
const int N = 1e6 + 1, mod = 998244353;
const ll inf = 1e9;
double eps = 1e-15;
bool flg = 0;
void slv() {
int n, m, k;
cin >> n >> m >> k;
int a[n + 1], b[m + 1], sum = 0;
for (int i = 1; i <= n; i++) {
cin >> a[i];
if (a[i] < k) {
cout << "Impossible";
return;
}
sum += a[i];
}
for (int i = 1; i <= m; i++)
cin >> b[i];
int ans = inf;
for (int msk = 0; msk < (1 << m); msk++) {
vector<int> s;
int val = 0, val2 = 0;
for (int i = 0; i < m; i++) {
if (msk >> i & 1) {
val2 += min(b[i + 1], n);
val += b[i + 1];
}
}
if (val >= sum && val2 >= n * k) ans = min(ans, val);
}
if (ans == inf) cout << "Impossible";
else cout << ans - sum;
}
main() {
//freopen("input.txt", "r", stdin);
//freopen("output.txt", "w", stdout);
ios_base::sync_with_stdio(0);
cin.tie(0);
int tp = 1;
if (flg) cin >> tp;
while (tp--) {
slv();
}
}
//wenomechainsama
