#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
const ll INF = 1e9+7;
const ll MOD = 998244353;
typedef pair<ll,ll> ii;
#define iii pair<ll,ii>
#define f(i,a,b) for(ll i = a;i < b;i++)
#define pb push_back
#define vll vector<ll>
#define F first
#define S second
#define all(x) (x).begin(), (x).end()
///I hope I will get uprating and don't make mistakes
///I will never stop programming
///sqrt(-1) Love C++
///Please don't hack me
///@TheofanisOrfanou Theo830
///Think different approaches (bs,dp,greedy,graphs,shortest paths,mst)
///Stay Calm
///Look for special cases
///Beware of overflow and array bounds
///Think the problem backwards
///Training
int main(void){
ll n,m,k;
cin>>n>>m>>k;
ll a[n];
ll ans = 1e18;
ll cur = 0;
f(i,0,n){
cin>>a[i];
cur += a[i];
if(a[i] < k){
cout<<"Impossibe\n";
return 0;
}
}
ll b[m];
ll sum = 0;
f(i,0,m){
cin>>b[i];
sum += b[i];
}
ll dp[m+1][sum+1];
f(i,0,m+1){
f(j,1,sum+1){
dp[i][j] = -1e18;
}
}
dp[0][0] = 0;
f(i,0,m){
f(j,0,sum+1){
dp[i+1][j] = dp[i][j];
}
f(j,0,sum+1){
if(j + b[i] <= sum){
dp[i+1][j + b[i]] = max(dp[i+1][j + b[i]],dp[i][j] + min(n,b[i]));
}
}
}
f(j,cur,sum+1){
if(dp[m][j] >= n * k){
cout<<j - cur<<"\n";
return 0;
}
}
cout<<"Impossible\n";
}
