#include<bits/stdc++.h>
using namespace std;
#define int long long
#define all(x) x.begin(),x.end()
#define ff first
#define ss second
#define pb push_back
signed main(){
ios_base::sync_with_stdio(0);
cin.tie(0);cout.tie(0);
int n,m,k;
cin>>n>>m>>k;
vector <int> a(n+1),b(m+1);
int suma=0,sumb=0;
for(int i=1;i<=n;i++){
cin>>a[i];
suma+=a[i];
}
for(int i=1;i<=m;i++){
cin>>b[i];
sumb+=b[i];
}
for(int i=1;i<=n;i++){
if(a[i]<k){
cout<<"Impossible\n";
return 0;
}
}
vector <vector <int > > dp(m+1, vector <int> (sumb+1,-1));
dp[0][0]=0;
for(int i=1;i<=m;i++){
dp[i][0]=0;
for(int j=b[i];j<=sumb;j++){
int mx=-1;
if(dp[i-1][j-b[i]]!=-1){
mx=max(mx,dp[i-1][j-b[i]]+min(n,b[i]));
}
if(dp[i-1][j]!=-1){
mx=max(mx,dp[i-1][j]);
}
dp[i][j]=mx;
}
//cout<<"\n";
}
int mn=1e18;
for(int i=1;i<=m;i++){
for(int j=suma;j<=sumb;j++){
if(dp[i][j]!=-1 && dp[i][j]>=n*k){
mn=min(mn,j-suma);
}
}
}
if(mn==1e18){
cout<<"Impossible\n";
return 0;
}
cout<<mn<<"\n";
}
/*
*/
