#include <bits/stdc++.h>
using namespace std;
//------------------------------DEFINE------------------------------
//******************************************************************
#define IOS ios_base::sync_with_stdio(false); cin.tie(0),cout.tie(0)
#define ll long long
#define pb push_back
#define F first
#define S second
#define INF 1e18
#define all(v) (v).begin(),(v).end()
#define rall(v) (v).rbegin(),(v).rend()
#define pii pair<int,int>
#define pll pair<ll,ll>
#define OK cout<<"Ok"<<endl;
#define MOD (ll)(1e9+7)
#define endl "\n"
//******************************************************************
//----------------------------FUNCTION------------------------------
//******************************************************************
ll gcd(ll a,ll b){
if(a>b) swap(a,b);
if(a==0) return a+b;
return gcd(b%a,a);
}
ll lcm(ll a,ll b){
return a/gcd(a,b)*b;
}
bool is_prime(ll n){
ll k=sqrt(n);
if(n==2) return true;
if(n<2||n%2==0||k*k==n) return false;
for(int i=3;i<=k;i+=2){
if(n%i==0){
return false;
}
}
return true;
}
//*****************************************************************
//--------------------------MAIN-CODE------------------------------
const int mxn=2e5+5;
int t=1,n,m,k,arr[mxn],b[mxn],sum,x;
bool q=false;
void solve(){
cin>>m>>n>>k;
for(int i=1;i<=m;i++){
cin>>b[i];
sum+=b[i];
if(b[i]<k){
q=true;
}
}
for(int i=1;i<=n;i++){
cin>>arr[i];
x+=arr[i];
}
if(n<k||x<sum){
q=true;
}
if(q){
cout<<"Impossible"<<endl;
return;
}
if(k==1){
sort(arr+1,arr+n+1);
map<int,bool>mp;
mp[0]=1;
for(int i=1;i<=n;i++){
vector<int>vt;
for(auto it=mp.begin();it!=mp.end();it++){
int x=it->F;
vt.pb(x+arr[i]);
}
for(int v:vt){
mp[v]=true;
}
}
int ans=1e7;
for(auto it=mp.begin();it!=mp.end();it++){
int x=it->F;
if(x>=sum){
ans=min(ans,x-sum);
}
}
if(ans==1e7){
cout<<"Impossible"<<endl;
}
else{
cout<<ans<<endl;
}
return;
}
map<int,int>mp;
mp[0]=0;
sort(arr+1,arr+n+1);
for(int i=1;i<=n;i++){
//if(arr[i]>=k){
vector<pii>vt;
for(auto it=mp.begin();it!=mp.end();it++){
vt.pb({it->F+arr[i],it->S+min(arr[i],m)});
}
for(pii v:vt){
mp[v.F]=max(mp[v.F],v.S);
}
//}
}
int ans=1e7;
for(auto it=mp.begin();it!=mp.end();it++){
//cout<<it->F<<' '<<it->S<<endl;
if(it->F>=sum&&it->S>=m*k){
ans=min(ans,(it->F)-sum);
}
}
if(ans==1e7){
cout<<"Impossible"<<endl;
return;
}
cout<<ans<<endl;
}
int main(){
IOS;
//cin>>t;
while(t--){
solve();
}
return 0;
}
