#include <bits/stdc++.h>
/// author: LilPluton auuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuu
#define OPT ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
#define intt long long
#define ll long long
#define pb push_back
#define arr array
#define vll vector<int>
#define fi first
#define se second
#define rep(i,j,k) for(int i = j; i <= k; ++i)
#define all(a) a.begin(),a.end()
#define pii pair<int,int>
#define endll '\n'
using namespace std;
const ll INF = 1e18;
const int N = 1e5 + 5;
ll n, m, k, sum, chefsum;
ll a[N], chef[N];
ll dp[N];
signed main()
{
cin >> n >> m >> k;
for(ll i = 1; i <= n; ++i)
cin >> a[i], sum += a[i];
sort(a + 1, a + n + 1);
for(ll i = 1; i <= m; ++i)
cin >> chef[i], chefsum += chef[i];
sort(chef + 1, chef + m + 1);
if(k == 1)
{
dp[0] = 1;
for(int i = 1; i <= m; ++i)
{
for(int j = N; j >= chef[i]; --j)
{
if(dp[j - chef[i]])
dp[j] = 1;
}
}
for(ll i = sum; i <= N; ++i)
{
if(dp[i])
{
cout << i - sum << endll;
return 0;
}
}
cout << "Impossible" << endll;
return 0;
}
if(m < k || a[1] < k)
{
cout << "Impossible" << endll;
return 0;
}
ll ans = INF;
for(ll mask = 1; mask < (1 << m); ++mask)
{
ll x = __builtin_popcount(mask);
if(x < k)
continue;
ll s = 0, extra = 0;
for (ll i = 0;i < m;i++) {
if ((1 << i) & mask) {
extra += chef[i + 1];
if (s < n * k) {
s += min(n * k - s, min(chef[i + 1], n));
}
}
}
if (extra >= sum && s == n * k)
ans = min(ans, extra - sum);
}
if(ans == INF)
cout << "Impossible";
else
cout << ans << endll;
}
