// In the name of God
#include<bits/stdc++.h>
using namespace std;
#define pb push_back
#define fi first
#define se second
typedef long long ll;
const int N = 300 + 5, MOD = 1e9 + 7;
int n, A[N], B[N], k, m;
bitset<N * N> dp;
int dp2[N * N], suf[N * N + 10];
void solve() {
cin >> n >> m >> k;
for (int i = 0; i < n; i++)
cin >> A[i];
for (int i = 0; i < m; i++)
cin >> B[i];
if (*min_element(A, A + n) < k) {
cout << "Impossible" << endl;
return;
}
vector<int> b, vec;
for (int i = 0; i < m; i++) {
if (B[i] < n)
b.pb(B[i]);
else
vec.pb(B[i]);
}
dp[0] = true;
for (auto x : b) {
dp |= dp << x;
}
fill(dp2, dp2 + N * N, -1e9);
dp2[0] = 0;
for (auto x : vec) {
for (int s = N * N - 1; s >= x; s--) {
dp2[s] = max(dp2[s - x] + 1, dp2[s]);
}
}
suf[N * N] = -1;
for (int i = N * N - 1; i >= 0; i--) {
suf[i] = suf[i + 1];
if (dp[i])
suf[i] = i;
}
int sumA = accumulate(A, A + n, 0);
int ans = 1e9 + 5;
for (int s = 0; s < N * N; s++) {
if (dp2[s] >= 0 && suf[max(0, max(sumA - s, n * (k - dp2[s])))] != -1) {
ans = min(ans, s + suf[max(0, max(sumA - s, n * (k - dp2[s])))] - sumA);
}
}
if (ans < 1e9) {
cout << ans << endl;
}
else
cout << "Impossible\n";
}
int32_t main() {
ios::sync_with_stdio(0), cin.tie(0), cout.tie(0);
solve();
return 0;
}
