// Born_To_Laugh - Hughie Do
#include <bits/stdc++.h>
using namespace std;
const int MAX_W = 300005;
const int INF = 1e9 + 7;
int n, m, k;
int dp[MAX_W];
void solve(){
if(!(cin >> n >> m >> k)) return;
long long sum_needed = 0;
bool impossible = false;
for(int i = 1; i <= n; ++i){
int x; cin >> x;
sum_needed += x;
if(x < k) impossible = true;
}
vector<int> chefs(m);
long long sum_capacity = 0;
for(int i = 0; i < m; ++i){
cin >> chefs[i];
sum_capacity += chefs[i];
}
if(impossible || sum_capacity < sum_needed || m < k){
cout << "Impossible\n";
return;
}
fill(dp, dp + MAX_W, -INF);
dp[0] = 0;
int current_sum = 0;
for(int time : chefs){
for(int j = current_sum; j >= 0; --j){
if(dp[j] != -INF){
if(j + time < MAX_W){
dp[j + time] = max(dp[j + time], dp[j] + 1);
}
}
}
current_sum = min(current_sum + time, MAX_W - 1);
}
int limit = min((long long)MAX_W - 1, sum_capacity);
for(int i = sum_needed; i <= limit; ++i){
if(dp[i] >= k){
cout << i - sum_needed << '\n';
return;
}
}
cout << "Impossible\n";
}
int main(){
ios_base::sync_with_stdio(false);
cin.tie(nullptr);
solve();
return 0;
}
