/*************************************
* Author: Alice_in_Wonderland^^
*************************************/
#include <bits/stdc++.h>
using namespace std;
#define int long long
#define FOR(i, l, r) for (int i = (l); i <= (r); i++)
#define FOD(i, r, l) for (int i = (r), _l = (l); i >= _l; i--)
#define pii pair<int,int>
#define endl '\n'
#define pb push_back
#define TIME (1.0 * clock() / CLOCKS_PER_SEC)
const int N = 300 * 300 + 5;
const int MOD = 1e9 + 7;
const int block = 470;
const int LOG = 21;
const int INF = 1e18;
template<class A, class B>
bool umin(A& var, const B& val){ return (val < var) ? (var = val, true) : false; }
template<class A, class B>
bool umax(A& var, const B& val){ return (var < val) ? (var = val, true) : false; }
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
template<class X, class Y> int random(const int& l, const int& r) {
return uniform_int_distribution<int>(l,r)(rng);
}
#define DBG(x) cerr << #x << " = " << x << ' ';
#define DBGn(x) cerr << #x << " = " << x << '\n';
int n , m , k;
int a[N];
int b[N];
int mn_val = INF;
int sum = 0;
int sum2 = 0;
int dp[N];
void solve(void) {
cin >> n >> m >> k;
FOR(i , 0 , n - 1) {
cin >> a[i];
mn_val = min(mn_val , a[i]);
sum += a[i];
}
FOR(i , 0, m - 1) {
cin >> b[i];
sum2 += b[i];
}
if(mn_val < k){
cout << "Impossible";
return;
}
FOR(i , 0, N - 1) dp[i] = -N;
dp[0] = 0;
FOR(i , 0 , m - 1){
FOD(j , sum2 , 0){
if(b[i] + j <= N){
dp[b[i] + j] = max(dp[b[i] + j] , dp[j] + min(b[i] , n));
}
}
}
FOR(i , sum , N){
if(dp[i] >= n * k){
cout << i - sum;
return;
}
}
cout << "Impossible";
}
signed main(void) {
if (fopen("TASK.INP", "r")) {
freopen("TASK.INP", "r", stdin);
freopen("TASK.OUT", "w", stdout);
}
ios_base::sync_with_stdio(false);
cin.tie(NULL);
int testCase = 1;
//cin >> testCase;
FOR(i ,1 ,testCase){
solve();
}
cerr << "Time elapsed: " << TIME << "s.\n";
return 0;
}
