//#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 = 2e5 + 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], v = 0;
for (int i = 0; i < n; i++) {
cin >> a[i];
v += a[i];
if (a[i] < k) {
cout << "Impossible";
return;
}
}
int w = 90000;
int b[m], pr[w + 1];
vector<int> dp(w + 1, -inf);
dp[0] = 0;
for (int i = 0; i < m; i++) {
cin >> b[i];
for (int j = w; j >= b[i]; j--) {
if (dp[j] < dp[j - b[i]] + 1) {
dp[j] = dp[j - b[i]] + 1;
pr[j] = i;
}
}
}
for (int x = v; x <= w; x++) {
if (dp[x] < k) continue;
vector<int> s;
int y = x;
while (y) {
s.push_back(b[pr[y]]);
y -= b[pr[y]];
}
bool ok = 1;
for (int i = 0; i < n; i++) {
sort(all(s));
if (!s[sz(s) - k]) {
ok = 0;
break;
}
for (int j = sz(s) - k; j < sz(s); j++)
s[j]--;
}
if (ok) {
cout << x - v;
return;
}
}
cout << "Impossible";
}
main() {
//freopen("rsq.in", "r", stdin);
//freopen("rsq.out", "w", stdout);
ios_base::sync_with_stdio(0);
cin.tie(0);
int tp = 1;
if (flg) cin >> tp;
while (tp--) {
slv();
}
}
//wenomechainsama
