#include<bits/stdc++.h>
using namespace std;
#define F first
#define S second
#define endl '\n'
typedef long long ll;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
const int N = 305, M = 1e5 + 50;
int n, m, k, a[N], b[N];
bitset<M> bs;
void solve() {
cin >> n >> m >> k;
int s = 0;
for (int i = 1; i <= n; i++) {
cin >> a[i];
s += a[i];
}
for (int i = 1; i <= m; i++) {
cin >> b[i];
}
bs[0] = 1;
for (int i = 1; i <= m; i++) {
bs = bs|(bs<<b[i]);
}
int ans = bs._Find_next(s-1);
if (ans >= M) cout << "Impossible" << endl;
else cout << ans-s << endl;
}
int main() {
ios::sync_with_stdio(0), cin.tie(0), cout.tie(0);
solve();
return 0;
}
