#include <bits/stdc++.h>
#define ll long long
#define nl "\n"
#define yes "YES"
#define no "NO"
#define all(v) v.begin(),v.end()
#define fast ios_base::sync_with_stdio(false);cin.tie(NULL);
using namespace std;
const ll N=301;
ll n,m,k;
vector<ll>a,b;
ll dp[N+10][N*N+10];
ll solve(ll i,ll j){
if(j<0)return -1e14;
if(i==m)return 0;
if(dp[i][j]!=-1)return dp[i][j];
ll op1=solve(i+1,j);
ll op2=solve(i+1,j-b[i])+min(b[i],n);
return dp[i][j]=max(op1,op2);
}
int main() {
fast
memset(dp,-1, sizeof(dp));
cin>>n>>m>>k;
a=vector<ll>(n);
b=vector<ll>(m);
ll sm=0,sm2=0;
bool ok=1;
for(ll &i:a)cin>>i,sm+=i,ok&=(i>=k);
for(ll &i:b)cin>>i,sm2+=i;
if(!ok){
cout<<"Impossible"<<nl;
return 0;
}
for(ll i=sm;i<=sm*sm;i++){
if(solve(0,i)>=n*k){
cout<<i-sm<<nl;
return 0;
}
}
cout<<"Impossible"<<nl;
return 0;
}
