#include <bits/stdc++.h>
using namespace std;
const int MAXN = 310;
int a[MAXN], b[MAXN], dp[2][MAXN * MAXN];
int main(){
cin.tie(0)->sync_with_stdio(0);
int n, m, k; cin >> n >> m >> k;
int s_a = 0, s_b = 0;
for(int i=1; i<=n; i++){
cin >> a[i];
s_a += a[i];
}
for(int i=1; i<=m; i++){
cin >> b[i];
s_b += b[i];
}
for(int i=1; i<=n; i++){
if(a[i] < k){
cout << "Impossible\n";
return 0;
}
}
for(int i=0; i<2; i++){
for(int sum_b=0; sum_b<=s_b; sum_b++){
dp[i][sum_b] = -1e9;
}
}
int ans = 1e9;
dp[0][0] = 0;
for(int i=1; i<=m; i++){
for(int sum_b=0; sum_b<=s_b; sum_b++){
dp[i % 2][sum_b] = dp[1 - i % 2][sum_b];
if(b[i] <= sum_b){
dp[i % 2][sum_b] = max(dp[i % 2][sum_b], dp[1 - i % 2][sum_b - b[i]] + min(n, b[i]));
}
// cout << i << " " << sum_b << " " << dp[i % 2][sum_b] << "\n";
if(sum_b >= s_a && dp[i % 2][sum_b] >= n * k){
ans = min(ans, sum_b - s_a);
}
}
}
if(ans == 1e9){
cout << "Impossible\n";
return 0;
}
cout << ans << "\n";
return 0;
}
