#include <bits/stdc++.h>
using namespace std;
const int MAXN = 301;
const int MAXS = MAXN*MAXN+1000;
int dp[MAXN][MAXS], n, m, k;
void solve() {
vector<int> a(n+1), b(m+1);
int need = 0;
for (int i = 1; i <= n; i++) {
cin >> a[i];
need += a[i];
}
for (int j = 1; j <= m; j++) {
cin >> b[j];
}
int ans = INT_MAX;
for (int bits = 0; bits < (1 << m); bits++) {
int x = bits<<1;
int sum = 0, chefs = 0, bad_chefs = 0, good_chefs = 0;
for (int i = 1; i <= m; i++) {
if ((x>>i)&1) {
sum += b[i]; chefs++;
if (b[i] < n) bad_chefs += b[i];
else good_chefs++;
}
}
bool good = int(bad_chefs/n) + good_chefs >= k;
for (int i = 1; i <= n; i++) {
if (a[i] < k) good = false;
}
if (good && sum >= need) {
ans = min(ans, sum-need);
}
}
if (ans == INT_MAX)
cout << "Impossible\n";
else
cout << ans << "\n";
}
int main() {
ios::sync_with_stdio(0); cin.tie(0);
cin >> n >> m >> k;
if (k != 1) {
solve();
return 0;
}
vector<int> a(n+1), b(m+1);
int sum = 0;
for (int i = 1; i <= n; i++) {
cin >> a[i]; sum += a[i];
}
for (int j = 1; j <= m; j++) {
cin >> b[j];
}
dp[0][0] = true;
for (int i = 1; i <= m; i++) {
for (int j = 0; j < MAXS; j++) {
dp[i][j] = dp[i-1][j];
}
for (int j = b[i]; j < MAXS; j++) {
if (dp[i-1][j-b[i]]) {
dp[i][j] = true;
}
}
}
for (int i = 0; i < MAXS; i++) {
if (dp[m][i]) cerr << i << " ";
}
for (int i = sum; i < MAXS; i++) {
if (dp[m][i]) {
cout << i-sum << "\n";
return 0;
}
}
cout << "Impossible\n";
return 0;
}
