#include <bits/stdc++.h>
#define sz(x) (int)x.size()
#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(), x.rend()
//#define int long long
using namespace std;
using ll = long long;
using ull = unsigned long long;
using ld = long double;
using pii = pair<int, int>;
using pll = pair<ll, ll>;
const int mod = 1e9 + 7;
const int LOG = 20;
const int maxn = 1e5 + 5;
const double eps = 1e-9;
int dp[305][305*305];
int32_t main() {
int n, m, k;
cin >> n >> m >> k;
vector<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];
sort(A.begin() + 1, A.end());
sort(B.begin() + 1, B.end());
if(A[1] < k || m < k) {
cout << "Impossible\n";
return 0;
}
if(k == 1) {
ll sum = 0;
for(int i=1; i<=n; i++) sum += A[i];
bitset<maxn> bs;
bs[0] = 1;
for(int i=1; i<=m; i++) bs |= (bs << B[i]);
for(int i=sum; i<=300*300; i++) {
if(bs[i]) {
cout << i - sum << '\n';
return 0;
}
}
cout << "Impossible\n";
return 0;
}
if(m <= 20) {
ll ans = 1e18;
ll sum = 0;
for(int i=1; i<=n; i++) sum += A[i];
//cout << sum << '\n';
for(int s=1; s<(1<<(m+1)); s++) {
if(s & 1) continue;
if(__builtin_popcount(s) < k) continue;
int sum2=0, area=0;
for(int i=1; i<=m; i++) {
if(s & (1 << i)) {
sum2 += B[i];
if(area < n * k) area += min(B[i], n);
}
}
if(sum2 >= sum && area >= n * k) ans = min(ans, sum2 - sum);
}
if(ans == 1e18) cout << "Impossible\n";
else cout << ans << '\n';
return 0;
}
ll sumA = 0, sumB = 0;
for(int i=1; i<=n; i++) sumA += A[i];
for(int i=1; i<=m; i++) sumB += B[i];
for(int i=1; i<=m; i++) {
for(int j=0; j<=sumB; j++) {
dp[i][j] = dp[i-1][j];
if(j >= B[i]) dp[i][j] = max(dp[i][j], dp[i-1][j-B[i]] + min(n, B[i]));
}
}
for(int i=sumA; i<=sumB; i++) {
if(dp[m][i] >= n * k) {
cout << i - sumA << '\n';
return 0;
}
}
cout << "Impossible\n";
return 0;
}
