/*
cf : F112
/) /) ~ ┏━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┃
( •-• ) ~ ♡ You are amazing ♡
/ づづ ~ ┗━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┛
*/
#include <bits/stdc++.h>
using namespace std;
#define F first
#define S second
#define int long long
#define Ali ios::sync_with_stdio(false), cin.tie(0), cout.tie(0)
const int N = 3e2 + 7;
const int P = 233;
const int len = 250;
const int MOD = 1e9 + 7;
const int inf = 1e18;
int gcd(int x, int y){
while(y){
x %= y;
swap(x, y);
}
return x;
}
int binpow(int n, int k){
if (k == 0) return 1;
if (k % 2 == 0){
int val = binpow(n, k / 2);
return (val * val) % MOD;
}
return (n * binpow(n, k - 1)) % MOD;
}
vector < vector < int > > dp(N, vector < int > (N * N));
void abb(){
int n, m, k;
cin >> n >> m >> k;
vector < int > a(n + 1);
vector < int > b(m + 1);
bool ok = true;
int suma = 0, sumb = 0;
for (int i = 1; i <= n; ++i) cin >> a[i], ok &= (a[i] >= k), suma += a[i];
for (int i = 1; i <= m; ++i) {
cin >> b[i]; sumb += b[i];
}
if (ok == false){
cout << "Impossible\n";
return;
}
for (int sum = 1; sum <= sumb; ++sum){
for (int i = 1; i <= m; ++i){
dp[i][sum] = dp[i - 1][sum];
if (sum - b[i] >= 0) dp[i][sum] = max(dp[i][sum], dp[i - 1][sum - b[i]] + min(b[i], n));
}
}
for (int sum = suma; sum <= sumb; ++sum){
// cout << dp[m][sum] << " ";
if (dp[m][sum] >= k * n){
cout << sum - suma << "\n";
return;
}
}
// cout << "\n";
cout << "Impossible";
}
/*
4 4 1
1 2 3 4
10 1 2 7
*/
signed main(){
Ali;
int T = 1;
// cin >> T;
while(T--){
abb();
}
}
