#include <bits/stdc++.h>
#define SZ(x) ((int)x.size())
#define fi first
#define se second
#define pb push_back
#define FOR(i, a, b) for (int i = a, _b = b; i <= _b; ++i)
#define FORD(i, a, b) for (int i = a, _b = b; i >= _b; --i)
#define FORLL(i, a, b) for (ll i = a, _b = b; i <= _b; ++i)
#define FORDLL(i, a, b) for (ll i = a, _b = b; i >= _b; --i)
#define all(x) x.begin(), x.end()
#define uni(x) sort(all(x)), x.erase(unique(all(x)), x.end())
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
#define dbg(...) debug(#__VA_ARGS__, __VA_ARGS__)
template<typename T>
void __print_one(const char *&s, const T &x)
{
while (*s == ' ') ++s;
const char *p = s;
int bal = 0;
while (*s)
{
if (*s == '(') ++bal;
else if (*s == ')') --bal;
else if (*s == ',' && bal == 0) break;
++s;
}
cerr.write(p, s - p) << " = " << x;
if (*s == ',')
{
++s;
cerr << " , ";
}
}
template<typename... Args>
void debug(const char *s, Args... args)
{
cerr << "[ ";
int dummy[] = { 0 , ( __print_one(s, args) , 0 )... };
(void)dummy;
cerr << " ]\n\n";
}
template<class X>
bool maximize(X &a, X b)
{
if (a < b)
{
a = b;
return true;
}
return false;
}
template<class X>
bool minimize(X &a, X b)
{
if (a > b)
{
a = b;
return true;
}
return false;
}
// --------------------------------------------------------------------------------------------
const int maxn = 305;
int n, m, K, a[maxn], b[maxn], dp[maxn * maxn];
// --------------------------------------------------------------------------------------------
bool solve()
{
cin >> n >> m >> K;
if (K > m)
return false;
int sumA = 0, sumB = 0;
FOR(i, 0, n - 1)
{
cin >> a[i];
sumA += a[i];
if (a[i] < K)
return false;
}
FOR(i, 0, m - 1)
{
cin >> b[i];
sumB += b[i];
}
sort(a, a + n);
sort(b, b + m);
if (sumB < sumA)
return false;
FOR(x, 1, sumB)
dp[x] = -1e9;
dp[0] = 0;
FOR(i, 0, m - 1)
{
FORD(x, sumB, b[i])
{
maximize(dp[x], dp[x - b[i]] + min(b[i], n));
}
}
int res = 1e9;
FORD(i, sumB, sumA)
if (dp[i] >= K * n)
minimize(res, i);
if (res >= int(1e9))
return false;
cout << res - sumA;
return true;
}
signed main()
{
ios_base::sync_with_stdio(false); cin.tie(NULL); cout.tie(NULL);
#define TASK "TEST"
if (fopen(TASK".INP", "r"))
{
freopen(TASK".INP", "r", stdin);
freopen(TASK".OUT", "w", stdout);
}
if (!solve())
cout << "Impossible";
return 0;
}
