#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using ld = long double;
const int N = 300;
int a[N+5];
int dp[N*N+5];
int mxm[N*N+5];
const int INF = 1000000000;
int main(){
ios_base::sync_with_stdio(false), cin.tie(0);
cout.precision(10);
cout << fixed;
int n, m, k;
int tot = 0;
cin >> n >> m >> k;
for(int i=1; i<=n; i++){
cin >> a[i];
tot += a[i];
if(a[i] < k){
cout << "Impossible\n";
return 0;
}
}
vector <int> small, large;
for(int i=1; i<=m; i++){
int x;
cin >> x;
if(x >= n) large.push_back(x);
else small.push_back(x);
}
for(auto x : small) for(int i=N*N; i>=x; i--) if(dp[i-x] == i - x) dp[i] = i;
dp[N*N+1] = INF;
for(int i=N*N; i>=1; i--) if(dp[i] != i) dp[i] = dp[i+1];
for(int i=1; i<=N*N+1; i++) mxm[i] = -INF;
for(auto x : large) for(int i=N*N; i>=x; i--) mxm[i] = max(mxm[i], mxm[i-x] + 1);
int res = INF;
for(int i=0; i<=N*N; i++) if(mxm[i] >= 0) res = min(res, i + dp[max(tot - i, n*max(0, k - mxm[i]))]);
if(res == INF) cout << "Impossible\n";
else cout << res - tot << "\n";
return 0;
}
