#include "bits/stdc++.h"
using namespace std;
typedef long long ll;
typedef long double ld;
typedef vector <int> vi;
typedef pair <ll,ll> pll;
typedef pair <int,int> pii;
typedef pair <int,pii> piii;
#define forr(_a,_b,_c) for(int _a = (_b); _a <= int (_c); ++_a)
#define ford(_a,_b,_c) for(int _a = (_b) + 1; _a --> int (_c);)
#define forf(_a,_b,_c) for(int _a = (_b); _a < int (_c); ++_a)
#define st first
#define nd second
#define pb push_back
#define mp make_pair
#define all(x) begin(x),end(x)
#define mask(i) (1LL << (i))
#define bit(x, i) (((x) >> (i)) & 1)
#define bp __builtin_popcountll
#define file "test"
template<class X, class Y>
bool minz(X &x, const Y &y) {
if (x > y) {
x = y;
return true;
} return false;
}
template<class X, class Y>
bool maxz(X &x, const Y &y) {
if (x < y) {
x = y;
return true;
} return false;
}
const int N = 3e2 + 5;
const ll oo = (ll) 1e16;
const ll mod = 1e9 + 7; // 998244353;
const int lmt = 300 * 300;
int n, m, k, a[N], b[N], dp[N][2 * lmt + 2];
int main(){
ios_base::sync_with_stdio(0); cin.tie(0);
#ifndef ONLINE_JUDGE
freopen(file".inp", "r", stdin); freopen(file".out", "w", stdout);
#endif
cin >> n >> m >> k;
int sum = 0;
forr (i, 1, n){
cin >> a[i];
sum += a[i];
}
sum -= n * k;
forr (i, 1, m){
cin >> b[i];
}
sort(a + 1, a + 1 + n);
if (a[1] < k){
cout << "Impossible\n";
return 0;
}
memset (dp, -63, sizeof dp);
dp[0][0] = 0;
forr (i, 1, m){
forr (j, 0, lmt){
if (dp[i - 1][j] < 0) continue;
int uwu = min(n * k - dp[i - 1][j], min(b[i], n));
maxz(dp[i][j + b[i] - uwu], dp[i - 1][j] + uwu);
maxz(dp[i][j], dp[i - 1][j]);
}
}
forr (i, sum, lmt){
if (dp[m][i] == n * k){
cout << i - sum << "\n";
return 0;
}
}
cout << "Impossible\n";
return 0;
}
/*
*/
