#include <bits/stdc++.h>
using namespace std;
#define MAXN 301
#define MAXM 45
#define int long long
int n,m,k;
int a[MAXN],b[MAXN];
int number[MAXN];
queue<int> q;
bool dp[MAXN*MAXN];
bool newdp[MAXN][MAXN*MAXN];
vector<int> grt;
int32_t main()
{
ios_base::sync_with_stdio(false);
ios::sync_with_stdio(false);
cin.tie(0);cout.tie(0);
cin>>n>>m>>k;
for (int i=1;i<=n;i++) cin>>a[i];
for (int i=1;i<=m;i++) cin>>b[i];
int suma=0;for (int i=1;i<=n;i++) suma+=a[i];
if (m<=15)
{
/// proslo za 31 poen
int answer=INT_MAX;
for (int maska=0;maska<(1<<m);maska++)
{
int sumb=0;for (int i=1;i<=n;i++) {number[i]=0;q.push(i);}
for (int bit=0;bit<m;bit++)
{
if (!(maska&(1<<bit))) continue;
sumb+=b[bit+1];
for (int num=1;num<=min(n,b[bit+1]);num++)
{
if (q.empty()) break;
int node=q.front();q.pop();
number[node]++;
if (number[node]<a[node]) q.push(node);
}
}
while (!q.empty()) q.pop();
bool valid=true;
for (int node=1;node<=n;node++)
{
if (number[node]<k) {valid=false;break;}
}
if (valid==true and sumb>=suma) answer=min(answer,sumb-suma);
}
if (answer==INT_MAX) {cout<<"Impossible"<<endl;return 0;}
else {cout<<answer<<endl;return 0;}
}
if (k==1)
{
/// proslo za 20 poena
dp[0]=true;for (int i=1;i<MAXN*MAXN;i++) dp[i]=false;
for (int i=1;i<=m;i++)
{
for (int val=MAXN*MAXN-1;val>=0;val--)
{
if (val+b[i]>=MAXN*MAXN) continue;
if (dp[val]) dp[val+b[i]]=true;
}
}
int answer=INT_MAX;
for (int val=suma;val<MAXN*MAXN;val++)
{
if (dp[val]) {answer=val-suma;break;}
}
if (answer==INT_MAX) {cout<<"Impossible"<<endl;return 0;}
else {cout<<answer<<endl;return 0;}
}
bool subtask4=true;
/*
if (n>40) subtask4=false;
if (m>40) subtask4=false;
if (k>40) subtask4=false;
for (int i=1;i<=n;i++)
{
if (a[i]>40) subtask4=false;
}
for (int i=1;i<=m;i++)
{
if (b[i]>40) subtask4=false;
}
*/
if (subtask4)
{
for (int i=1;i<=n;i++)
{
if (a[i]<k) {cout<<"Impossible"<<endl;return 0;}
}
grt.push_back(0);int sumb=0;for (int i=1;i<=m;i++) sumb+=b[i];
dp[0]=true;for (int val=1;val<=sumb;val++) dp[val]=false;
for (int i=1;i<=m;i++)
{
if (b[i]>=n) {grt.push_back(b[i]);continue;}
for (int val=sumb;val>=0;val--)
{
if (val+b[i]>=MAXN*MAXN) continue;
if (dp[val]==true) dp[val+b[i]]=true;
}
}
for (int number=0;number<(int)grt.size();number++)
{
for (int val=0;val<=sumb;val++) newdp[number][val]=false;
}
newdp[0][0]=true;
for (int pos=1;pos<(int)grt.size();pos++)
{
for (int number=(int)grt.size()-1;number>=1;number--)
{
for (int val=sumb;val>=0;val--)
{
if (val+grt[pos]>=MAXN*MAXN) continue;
if (newdp[number-1][val]==true) newdp[number][val+grt[pos]]=true;
}
}
}
int answer=INT_MAX;
for (int val=0;val<=sumb;val++)
{
if (dp[val]==false) continue;
int num_greater=k-val/n;
if (num_greater<0) num_greater=0;
else if (num_greater>=(int)grt.size()) continue;
int fali=max((long long)0,suma-val);
for (int value=fali;value<=min(sumb,suma+answer-1-val);value++)
{
bool indicator=false;
for (int broj=num_greater;broj<(int)grt.size();broj++)
{
if (newdp[broj][value]==true) {answer=min(answer,val+value-suma);indicator=true;break;}
}
if (indicator) break;
}
}
if (answer==INT_MAX) cout<<"Impossible"<<endl;
else cout<<answer<<endl;
return 0;
}
return 0;
}
