#include<bits/stdc++.h>
using namespace std;
#define F first
#define S second
#define endl '\n'
typedef long long ll;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
const int N = 305;
int n, m, k, a[N], b[N], c[N];
vector<int> vc;
void solve() {
cin >> n >> m >> k;
int sm = 0;
bool flg = 1;
for (int i = 1; i <= n; i++) {
cin >> a[i];
sm += a[i];
flg = flg&&(a[i] >= k);
}
for (int i = 1; i <= m; i++) {
cin >> b[i];
}
if (!flg) {
cout << "Impossible" << endl;
return;
}
int ans = 1e9;
for (int mask = 0; mask < (1<<m); mask++) {
vc.clear();
int sm2 = 0;
for (int i = 1; i <= m; i++) {
if (mask>>(i-1)&1) {
vc.push_back(b[i]);
sm2 += b[i];
}
}
if (sm2 < sm) continue;
sort(vc.begin(), vc.end());
int tmp = 0;
int t = 0;
for (int i = 0; i <= (int)vc.size()-k; i++) {
c[i] = vc[i] - tmp;
t += c[i];
tmp += c[i];
if (i >= k-1) tmp -= c[i-k+1];
}
if (t >= n) ans = min(ans, sm2-sm);
}
if (ans >= 1e9) {
cout << "Impossible" << endl;
return;
}
cout << ans << endl;
}
int main() {
ios::sync_with_stdio(0), cin.tie(0), cout.tie(0);
solve();
return 0;
}
