//#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];
int total = 0, 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];
total += b[i];
}
int dp[m + 1][total + 1];
for (int j = 1; j <= total; j++) dp[0][j] = -inf;
dp[0][0] = 0;
for (int i = 1; i <= m; i++) {
for (int j = 0; j <= total; j++) {
dp[i][j] = dp[i - 1][j];
if (b[i] <= j)
dp[i][j] = max(dp[i][j], dp[i - 1][j - b[i]] + min(n, b[i]));
}
}
for (int x = sum; x <= total; x++) {
if (dp[m][x] >= n * k) {
cout << x - sum;
return;
}
}
cout << "Impossible";
}
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
