#include <bits/stdc++.h>
using namespace std;
const int N = 305;
const int SM = N * N;
int n, m, k, a[N], b[N], dp_more[SM], dp_less[SM];
int main(){
cin >> n >> m >> k;
int need = 0;
for (int i = 0; i < n; i ++)
cin >> a[i], need += a[i];
for (int i = 0; i < m; i ++)
cin >> b[i];
sort(b, b + m);
sort(a, a + n);
if (a[0] < k){
cout << "Impossible\n";
return 0;
}
memset(dp_more, -1, sizeof dp_more);
memset(dp_less, -1, sizeof dp_less);
dp_more[0] = dp_less[0] = 0;
set<int> created;
created.insert(0);
for (int i = 0; i < m; i ++){
for (int sm = SM - 1; sm >= b[i]; sm --){
if (b[i] > n and ~dp_more[sm - b[i]]){
dp_more[sm] = max(dp_more[sm], dp_more[sm - b[i]] + 1);
}
else if (b[i] <= n and ~dp_less[sm - b[i]]){
dp_less[sm] = max(dp_less[sm], dp_less[sm - b[i]] + 1);
created.insert(sm);
}
}
}
int ans = 1e9;
for (int sm = 0; sm < SM; sm++){
int x = dp_more[sm];
if (x == -1) continue;
int left = max((k - x) * n, need - sm);
left = max(0, left);
auto ub = created.upper_bound(left - 1);
if (ub == created.end())
continue;
int used = (*ub) + sm;
ans = min(ans, used - need);
}
if (ans == 1e9)
cout << "Impossible\n";
else
cout << ans << endl;
}
