#include <bits/stdc++.h>
using namespace std;
// #undef _GLIBCXX_DEBUG // disable run-time bound checking, etc
// #pragma GCC optimize("Ofast,inline") // Ofast = O3,fast-math,allow-store-data-races,no-protect-parens
// #pragma GCC optimize ("unroll-loops")
// #pragma GCC target("bmi,bmi2,lzcnt,popcnt") // bit manipulation
// #pragma GCC target("movbe") // byte swap
// #pragma GCC target("aes,pclmul,rdrnd") // encryption
// #pragma GCC target("avx,avx2,f16c,fma,sse3,ssse3,sse4.1,sse4.2") // SIMD
// #include <bits/extc++.h>
// using namespace __gnu_pbds;
// template<class T>using ordered_set = tree<T, null_type, less<T>, rb_tree_tag,tree_order_statistics_node_update>;
// template<class T>using ordered_multiset = tree<T, null_type, less_equal<T>, rb_tree_tag,tree_order_statistics_node_update>;
#define ll long long
#define INF (ll)1e9+7
#define fo(i, n) for(int i=0;i<((ll)n);i++)
#define deb(x) cout << #x << " = " << x << endl;
#define deb2(x, y) cout << #x << " = " << x << ", " << #y << " = " << y << endl
#define pb push_back
#define mp make_pair
#define F first
#define S second
#define LSOne(S) ((S) & (-S))
#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(), x.rend()
inline int readint(){ int v = 0; char c; while((c = getchar()) != EOF && c != ' ' && c != '\n'){ v *= 10; v += c - '0'; } return v; }
inline int readintsigned() { int v = 0; int sign = 1; char c = getchar(); if (c == '-') { sign = -1; } else { v += c - '0'; } while ((c = getchar()) != EOF && c != ' ' && c != '\n') { v *= 10; v += c - '0'; } return v * sign; }
inline string readstring() { string s; char c; while ((c = getchar()) != EOF && c != '\n' && c != ' ') { s.push_back(c); } return s; }
template <class result_t=std::chrono::milliseconds,class clock_t=std::chrono::steady_clock,class duration_t = std::chrono::milliseconds>
auto since(std::chrono::time_point<clock_t, duration_t> const& start){return std::chrono::duration_cast<result_t>(clock_t::now() - start);}
typedef pair<int, int> pii;
typedef pair<ll, ll> pl;
typedef vector<int> vi;
typedef vector<ll> vl;
typedef vector<pii> vpii;
typedef vector<pl> vpl;
typedef vector<vi> vvi;
typedef vector<vl> vvl;
typedef vector<vpii> vvpii;
typedef vector<vpl> vvpl;
vi chefs;
ll slak = 0;
int n, m, k, val;
int memo[310][91000];
// int dp(int pos, int skipped = 0, int needDifferent = 0){
// int res = INF;
// if(!seen[pos+1][skipped]){
// dp(pos+1, skipped, );
// }
// return res;
// }
int main() {
// cout << fixed << setprecision(20);
// auto start = std::chrono::steady_clock::now(); // since(start).count()
cin.tie(0)->sync_with_stdio(0);
cin >> n >> m >> k;
int minDish = INF;
fo(i, n){
cin >> val;
minDish = min(minDish, val);
slak += val;
}
fo(i, m){
cin >> val;
chefs.pb(val);
}
sort(all(chefs));
if(minDish < k){
cout << "Impossible";
exit(0);
}
slak-=n*k;
memset(memo, -1, sizeof(memo));
memo[0][0] = 0;
fo(i, 90601){
fo(j, m+1){
int res = memo[j][i];
if(res == -1) continue;
if(i>=slak+n*k && res>=n*k){
cout << i-slak-n*k;
exit(0);
}
if(j == m) continue;
memo[j+1][i] = max(memo[j+1][i], res);
memo[j+1][i+chefs[j]] = max(memo[j+1][i+chefs[j]], res+min(chefs[j], n));
}
}
cout << "Impossible";
return 0;
}
