// In the name of Allah
#include <bits/stdc++.h>
using namespace std;
typedef long long int ll;
typedef long double ld;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
#define all(x) (x).begin(),(x).end()
#define len(x) ((ll) (x).size())
#define F first
#define S second
#define pb push_back
#define sep ' '
#define endl '\n'
#define Mp make_pair
#define debug(x) cerr << #x << ": " << x << endl;
#define kill(x) cout << x << '\n', exit(0);
#define set_dec(x) cout << fixed << setprecision(x);
#define file_io(x,y) freopen(x, "r", stdin); freopen(y, "w", stdout);
int n, m, k;
const int maxn = 300 + 5;
const int oo = 1e9;
int a[maxn], b[maxn];
pii dp[maxn][maxn * maxn];
pii GX(pii val, int x) {
if (val.F >= oo) return Mp(oo, 0);
if (x >= n) {
val.F--;
}
else {
val.S = x + val.S;
val.F -= (val.S / n);
val.S %= n;
}
return val;
}
pii cmp(pii a, pii b) {
if (a.F >= oo && b.F >= oo) return Mp(oo, 0);
else if (a.F >= oo) return b;
else if (b.F >= oo) return a;
int x = a.F * n - a.S, y = b.F * n - b.S;
if (x < y) return a;
else return b;
}
int main() {
ios::sync_with_stdio(false); cin.tie(0); cout.tie(0);
cin >> n >> m >> k;
for (int i = 1; i <= n; i++) cin >> a[i];
for (int i = 1; i <= m; i++) cin >> b[i];
int sm = 0;
for (int i = 1; i <= n; i++) {
if (a[i] < k) kill("Impossible");
sm += a[i];
}
for (int i = 0; i <= m; i++) {
dp[i][0] = Mp(k, 0);
for (int val = 1; val < maxn * maxn; val++) {
if (i == 0) dp[i][val] = Mp(oo, 0);
else {
if (val - b[i] >= 0) {
dp[i][val] = cmp(dp[i - 1][val], GX(dp[i - 1][val - b[i]], b[i]));
}
else dp[i][val] = dp[i - 1][val];
}
}
}
for (int val = sm; val < maxn * maxn; val++) {
if (dp[m][val].F <= 0) {
kill(val - sm);
}
}
cout << "Impossible" << endl;
return 0;
}
