#include<bits/stdc++.h>
#include<iostream>
#include<vector>
using namespace std;
#define ll long long
void rec(vector<int> &b, set<int> &sums, vector<int> lst, int k, int &m, int sm) {
if (k == 0) return;
int str = lst.empty() ? 0 : lst.back() + 1;
for (int i = str; i <= m - k; ++i) {
vector<int> cs(lst.begin(), lst.end());
cs.push_back(i);
if (k == 1) sums.insert(sm + b[i]);
rec(b,sums,cs,k-1,m,sm+b[i]);
}
}
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 ((*min_element(a.begin(),a.end())) < k) {
cout << "Impossible";
return;
}
sort(b.begin(),b.end(),greater<int>());
ll sm = 0;
for (int i = 0; i < k; i++)
{
sm += b[i];
}
set<int> sums;
vector<int> cs;
rec(b,sums,cs,k,m,0);
ll ans = 0;
for (int i = 0; i < n; i++)
{
bool ok = false;
for (int j = a[i]; j <= sm; j++)
{
if (sums.find(j) != sums.end()) {
ans += j-a[i];
ok = true;
break;
}
}
if (!ok) {
cout << "Impossible\n";
return;
}
}
cout << ans;
}
int main() {
ios_base::sync_with_stdio(false);
cin.tie();
int t = 1;
// cin >> t;
while (t--)
{
solve();
}
return 0;
}
