#include<bits/stdc++.h>
#include<iostream>
#include<vector>
using namespace std;
#define ll long long
void solve() {
int n,m,k;
cin >> n >> m >> k;
vector<int> a(n);
vector<int> b(m);
for (int i = 0; i < n; i++)
{
cin >> a[i];
}
for (int i = 0; i < m; i++)
{
cin >> b[i];
}
if (k > m || (*min_element(a.begin(),a.end())) < k) {
cout << "Impossible";
return;
}
sort(b.begin(),b.end(),greater<int>());
ll ans = 0;
for (int i = 0; i < n; i++)
{
multiset<int> lst;
int sm = 0;
for (int j = 0; j < k; j++)
{
lst.insert(b[j]);
sm+=b[j];
}
for (int j = k; j < m; j++)
{
auto ub = lst.upper_bound(sm-a[i]+b[j]);
if (ub == lst.end()) {
sm -= (*lst.rbegin());
sm += b[j];
lst.erase(prev(lst.end()));
lst.insert(b[j]);
} else if (ub == lst.begin()) {
continue;
} else {
sm -= (*prev(ub,1));
sm += b[j];
lst.erase(*prev(ub,1));
lst.insert(b[j]);
}
}
ans += sm-a[i];
}
cout << ans;
}
int main() {
ios_base::sync_with_stdio(false);
cin.tie();
int t = 1;
// cin >> t;
while (t--)
{
solve();
}
return 0;
}
