#include <bits/stdc++.h>
using namespace std;
//#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,tune=native")
//#pragma GCC optimize("Ofast,unroll-loops,fast-math,O3")
#define pb push_back
#define ll long long
#define sz(s) int(s.size()
#define all(v) v.begin(),v.end()
int mod = 1e8;
const int N = 2e5;
const int inf = 2e9;
vector <int> dp(N,INT_MIN);
signed main(){
//freopen("shuffle.in", "r", stdin);
//freopen("shuffle.out", "w", stdout);
ios_base::sync_with_stdio(0);
cin.tie(0);cout.tie(0);
int n,m,k;
cin >> n >> m >> k;
int a[n + 1],b[m + 1];
for(int i = 1; i <= n; i++) cin >> a[i];
for(int i = 1; i <= m; i++) cin >> b[i];
int ans = -1,sum = 0;
if(m < k){
cout << "Impossible";
return 0;
}
int w = 300 * 300;
for(int i = 1; i <= n; i++){
cin >> a[i];
sum += a[i];
if(a[i] < k){
cout << "Impossible";
return 0;
}
}
dp[0] = 0;
for(int i = 1; i <= m; i++){
for(int j = w; j >= b[i]; j--){
dp[j] = max(dp[j],dp[j - b[i]] + min(n,b[i]));
}
}
for(int i = 1; i <= w; i++){
if(i >= sum && dp[i] >= n * k){
ans = i - sum;
break;
}
}
if(ans == -1) cout << "Impossible";
else cout << ans;
}
