#include <bits/stdc++.h>
using namespace std;
#define int long long
#define double long double
#define FOR(i, l, r, d) for(int i=(l); i<=(r); i+=(d))
#define szof(x) ((int)(x).size())
#define vi vector<int>
#define pii pair<int, int>
#define F first
#define S second
#define pb push_back
#define eb emplace_back
#define mkp make_pair
const int INF = 1000000007;
const int LNF = INF*INF;
const int MOD = 1000000007;
const int mod = 998244353;
const double eps = 1e-12;
//#pragma GCC optimize("Ofast")
//#pragma GCC optimize("unroll-loops")
const int MAX = 302;
int n, m, lim; // meals, chefs, required chefs
int md, mw; // dian chefs, weak chefs
int meal[MAX], chef[MAX], meal_sum, dian_sum;
int chef_dian[MAX], chef_weak[MAX];
int dp_dian[MAX*MAX];
bool dp_weak[MAX*MAX];
int suf[MAX][MAX*MAX];
int res;
signed main(){
ios_base::sync_with_stdio(false);
cin.tie(0);
cout.tie(0);
cin>>n>>m>>lim;
FOR(i, 1, n, 1){
cin>>meal[i];
meal_sum += meal[i];
}
FOR(i, 1, m, 1){
cin>>chef[i];
if(chef[i] >= n) chef_dian[++md] = chef[i], dian_sum += chef[i];
else chef_weak[++mw] = chef[i];
}
// meal[i] >= lim
FOR(i, 1, n, 1){
if(meal[i] < lim){
cout<<"Impossible"<<'\n';
return 0;
}
}
// dp_dian
dp_dian[0] = 0;
FOR(i, 1, md*MAX, 1){
dp_dian[i] = -INF;
}
FOR(i, 1, md, 1){
for(int j=i*MAX; j>=chef_dian[i]; j--){
dp_dian[j] = max(dp_dian[j], dp_dian[j - chef_dian[i]] + 1);
}
}
// dp_weak
dp_weak[0] = 1;
FOR(i, 1, mw, 1){
for(int j=i*MAX; j>=chef_weak[i]; j--){
if(dp_weak[j - chef_weak[i]]) dp_weak[j] = 1;
}
}
// suf
for(int i=md; i>=0; i--){
for(int j=md*MAX; j>=0; j--){
suf[i][j] = INF;
}
}
FOR(i, 0, md*MAX, 1){
if(dp_dian[i] >= 0) suf[ dp_dian[i] ][i] = i;
}
for(int i=md; i>=0; i--){
for(int j=md*MAX; j>=0; j--){
if(i < md) suf[i][j] = min(suf[i][j], suf[i+1][j]);
if(j < md*MAX) suf[i][j] = min(suf[i][j], suf[i][j+1]);
}
}
/*
cerr<<"ok"<<endl;
cerr<<"dp_dian : "<<endl;
FOR(i, 0, 10, 1){
if(dp_dian[i] < -INF / 2) cerr<<"- ";
else cerr<<dp_dian[i]<<" ";
}
cerr<<endl;
cerr<<"suf : "<<endl;
FOR(i, 0, md, 1){
FOR(j, 0, 10, 1){
if(suf[i][j] >= INF) cerr<<"- ";
else cerr<<suf[i][j]<<" ";
}
cerr<<endl;
}
cerr<<endl;
cerr<<"dp_weak : "<<endl;
FOR(i, 0, 10, 1){
cerr<<dp_weak[i]<<" ";
}
cerr<<endl;
*/
res = INF;
// weak chefs + dian chefs
FOR(j, 0, meal_sum - 1, 1){
if(dp_weak[j] == 0) continue;
int req_chefs = max((int)0, lim - (j / n)); // required dian chefs
int req_sum = meal_sum - j; // required sum of time
//cerr<<"j = "<<j<<" ["<<req_chefs<<"]["<<req_sum<<"] "<<endl;
if(req_chefs > md or req_sum > dian_sum) continue;
res = min(res, j + suf[req_chefs][req_sum] - meal_sum);
}
// weak chefs only
FOR(j, meal_sum, mw*MAX, 1){
if(dp_weak[j]) res = min(res, j - meal_sum);
}
if(res < INF / 2) cout<<res<<'\n';
else cout<<"Impossible"<<'\n';
return 0;
}
