#include <bits/stdc++.h>
using namespace std;
int a[301], b[301];
int main() {
int n, m, k;
cin >> n >> m >> k;
if (k > m) {
cout << "Impossible\n";
return 0;
}
int sum = 0, need = 0;
for (int i = 0; i < n; ++i) {
cin >> a[i];
if (a[i] < k) {
cout << "Impossible\n";
return 0;
}
need += a[i];
}
for (int i = 0; i < m; ++i) {
cin >> b[i];
sum += b[i];
}
vector<vector<int>> dp(m + 1, vector<int>(sum + 1, INT_MIN));
dp[0][0] = 0;
for (int i = 0; i < m; ++i) {
for (int j = 0; j <= sum; ++j) {
dp[i + 1][j] = max(dp[i + 1][j], dp[i][j]);
}
for (int j = sum; j >= b[i]; --j) {
dp[i + 1][j] = max(dp[i + 1][j], dp[i][j - b[i]] + min(n, b[i]));
}
}
// for (int j = 0; j <= m; ++j) {
// for (int i = 0; i <= sum; ++i) {
// if (dp[j][i] < 0) cout << "- ";
// else cout << dp[j][i] << " ";
// }
// cout << endl;
// }
// cout << endl;
for (int i = need; i <= sum; ++i) {
if (dp[m][i] < n * k) continue;
cout << i - need << endl;
return 0;
}
cout << "Impossible\n";
}
