#include <bits/stdc++.h>
using namespace std;
const int MAXN = 310;
int a[MAXN], b[MAXN];
int main(){
cin.tie(0)->sync_with_stdio(0);
int n, m, k; cin >> n >> m >> k;
int s_a = 0;
for(int i=0; i<n; i++){
cin >> a[i];
s_a += a[i];
}
for(int i=0; i<m; i++){
cin >> b[i];
}
for(int i=0; i<n; i++){
if(a[i] < k){
cout << "Impossible\n";
return 0;
}
}
int ans = 1e9;
for(int mask=0; mask<(1 << m); mask++){
int s_b = 0, sum = 0;
for(int i=0; i<m; i++){
if(mask & (1 << i)){
s_b += b[i];
sum += min(n, b[i]);
}
}
if(s_a > s_b || k > __builtin_popcount(mask) || sum < n * k) continue;
ans = min(ans, s_b - s_a);
}
if(ans == 1e9){
cout << "Impossible\n";
} else cout << ans << "\n";
return 0;
}
