#include <bits/stdc++.h>
#pragma GCC optimize("O3,unroll-loops")
#pragma GCC target("avx2")
using namespace std;
#define int long long
#define pii pair<int,int>
#define ff first
#define ss second
#define sp << " " <<
#define all(cont) cont.begin(),cont.end()
#define vi vector<int>
const int inf = 1e17,N = 1e5+50,MOD = 1e9+7;
void solve() {
int n,m,k;
cin >> n >> m >> k;
vi a(n+1),b(m+1);
for (int i=1;i<=n;i++) cin >> a[i];
int s = 0;
for (int i=1;i<=n;i++) s+=a[i];
for (int i=1;i<=n;i++) {
if (a[i] < k) {
cout << "Impossible\n";
return;
}
}
for (int i=1;i<=m;i++) cin >> b[i];
int maxsm = 300*m;
int dp[m+1][maxsm+1]{};
for (int i=0;i<=m;i++) for (int j = 0;j<=maxsm;j++) dp[i][j] = -inf;
dp[0][0] = 0;
int ans = inf;
for (int i = 0;i<m;i++) {
for (int j = 0;j<=maxsm;j++) {
if (dp[i][j] == -inf) continue;
dp[i+1][j] = max(dp[i+1][j],dp[i][j]);
if (j+b[i+1] <= maxsm) dp[i+1][j+b[i+1]] = max(dp[i+1][j+b[i+1]],dp[i][j]+1);
}
}
for (int i = s;i<=maxsm;i++) {
if (dp[m][i] > k) {
ans = min(ans,i);
}
}
sort(b.begin()+1,b.end());
for (int i = 0;i<=m;i++) for (int j = 0;j<=maxsm;j++) dp[i][j] = -inf;
dp[0][0] = 0;
for (int i=0;i<m;i++) {
for (int j = 0;j<=maxsm;j++) {
if (dp[i][j] == -inf) continue;
dp[i+1][j] = max(dp[i+1][j],dp[i][j]);
if (b[i+1] >= k && j+b[i+1] <= maxsm) dp[i+1][j+b[i+1]] = max(dp[i+1][j+b[i+1]],dp[i][j]+1);
}
}
for (int i = s;i<=maxsm;i++) {
if (dp[m][i] >= k) {
ans = min(ans,i);
}
}
if (ans == inf) cout << "Impossible\n";
else cout << ans-s << '\n';
}
int32_t main() {
ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
#ifdef Dodi
freopen("in.txt","r",stdin);
freopen("out.txt","w",stdout);
#endif
int t = 1;
//cin >> t;
while (t --> 0) solve();
}
