#include <bits/stdc++.h>
using namespace std;
template <typename T> bool chkmax(T &x,T y){return x<y?x=y,true:false;}
template <typename T> bool chkmin(T &x,T y){return x>y?x=y,true:false;}
const int mx = 305, inf = 1e9+5;
int a[mx], b[mx], good[mx*mx], mi[mx][mx*mx], tot;
bitset<mx*mx> bs[mx];
int main() {
ios::sync_with_stdio(0);
cin.tie(0);
int n,m,k;
cin >> n >> m >> k;
bool ok = true;
for (int q = 1; q <= n; q++) {
cin >> a[q];
tot += a[q];
if (a[q] < k) ok = false;
}
vector<int> small, large;
for (int q = 1; q <= m; q++) {
cin >> b[q];
if (b[q] < n) small.push_back(b[q]);
else large.push_back(b[q]);
}
if (!ok) {
cout << "Impossible\n";
return 0;
}
good[0] = 1;
for (int q : small) {
for (int w = mx*mx-1; w >= 0; w--) if (w-q >= 0) good[w] |= good[w-q];
}
bs[0][0] = 1;
for (int q : large) {
for (int w = mx-1; w >= 1; w--) {
bs[w] |= (bs[w-1]<<q);
}
}
for (int q = mx-1; q >= 0; q--) {
for (int w = mx*mx-1; w >= 0; w--) {
mi[q][w] = inf;
if (bs[q][w]) mi[q][w] = w;
if (q < mx-1) chkmin(mi[q][w], mi[q+1][w]);
if (w < mx*mx-1) chkmin(mi[q][w], mi[q][w+1]);
}
}
int ans = inf;
for (int q = 0; q < mx*mx; q++) {
if (!good[q]) continue;
int f = (q >= n*k ? 0 : (n*k-q+n-1)/n), g = max(0,tot-q);
chkmin(ans, mi[f][g]+q);
}
if (ans == inf) cout << "Impossible\n";
else cout << ans-tot << '\n';
return 0;
}
