#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define fi first
#define se second
#define pb push_back
#define vi vector<int>
#define vl vector<ll>
#define pi pair<int, int>
#define pl pair<ll,ll>
#define all(x) (x).begin(),(x).end()
int main() {
ios::sync_with_stdio(0);
cin.tie(0);
int n,m,k;
cin >> n >> m >> k;
vi a(n);
vi b(m);
for (int i=0; i<n; i++) {
cin >> a[i];
}
for (int i=0; i<m; i++) {
cin >> b[i];
}
sort(all(b),[](int a, int b){return a>b;});
vi sum1(m,0),sum2(m,0);
for (int i=m-1; i>=0; i--) {
if (i!=m-1) {
sum1[i]+=sum1[i+1];
sum2[i]+=sum2[i+1];
}
sum1[i]+=b[i];
sum2[i]+=min(b[i],n);
}
int s=accumulate(all(b),0);
int s2=accumulate(all(a),0);
if (*min_element(all(a))<k || m<k || s<s2) {
cout << "Impossible\n";
return 0;
}
set<array<int,3>> q;
int ans=1e9;
q.insert({0,0,0});
while (q.size()) {
auto a=*q.begin();
q.erase(q.begin());
int i=a[0];
int j=a[1];
int l=a[2];
if (j>=n*k && l>=s2) {
ans=min(ans,l-s2);
continue;
}
if (i==m) {
continue;
}
if (j+sum2[i]<n*k || l+sum1[i]<s2) {
continue;
}
q.insert({i+1,j,l});
q.insert({i+1,min(j+min(n,b[i]),min(s,n*k)),l+b[i]});
}
if (ans==1e9) {
cout << "Impossible\n";
}
else {
cout << ans << '\n';
}
return 0;
}
