// subtask 1
#include "bits/stdc++.h"
#define ff first
#define ss second
#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()
#define sz(x) (int)(x).size()
using namespace std;
using ll = long long;
using pii = pair<int, int>;
const char nl = '\n';
const ll LINF = 0x3f3f3f3f3f3f3f3f;
const int INF = 0x3f3f3f3f;
int main() {
ios::sync_with_stdio(0), cin.tie(0);
int n, m, k; cin >> n >> m >> k; // 1 <= m <= 2
vector<int> a(n); for (auto &x : a) cin >> x;
vector<int> b(m); for (auto &x : b) cin >> x;
int sumA = accumulate(all(a), 0);
int sumB = accumulate(all(b), 0);
if (sumB < sumA || m < k || *min_element(all(a)) < k) {
cout << "Impossible" << nl;
return 0;
}
if (m == 1) {
if (k == 1 && b[0] >= sumA)
cout << b[0] - sumA << nl;
else
cout << "Impossible" << nl;
}
if (m == 2) {
if (k == 1) {
int ans = INF;
if (b[0] >= sumA) ans = min(ans, b[0] - sumA);
if (b[1] >= sumA) ans = min(ans, b[1] - sumA);
if (b[0] + b[1] >= sumA) ans = min(ans, b[0] + b[1] - sumA);
if (ans == INF)
cout << "Impossible" << nl;
else
cout << ans << nl;
} else if (k == 2) {
if (b[0] + b[1] >= sumA && b[0] >= n && b[1] >= n)
cout << b[0] + b[1] - sumA << nl;
else
cout << "Impossible" << nl;
} else {
cout << "Impossible" << nl;
}
}
return 0;
}
