#include <bits/stdc++.h>
using namespace std;
void __print(int x) {cerr << x;}
void __print(long x) {cerr << x;}
void __print(long long x) {cerr << x;}
void __print(unsigned x) {cerr << x;}
void __print(unsigned long x) {cerr << x;}
void __print(unsigned long long x) {cerr << x;}
void __print(float x) {cerr << x;}
void __print(double x) {cerr << x;}
void __print(long double x) {cerr << x;}
void __print(char x) {cerr << '\'' << x << '\'';}
void __print(const char *x) {cerr << '\"' << x << '\"';}
void __print(const string &x) {cerr << '\"' << x << '\"';}
void __print(bool x) {cerr << (x ? "true" : "false");}
template<typename T, typename V>
void __print(const pair<T, V> &x) {cerr << '{'; __print(x.first); cerr << ','; __print(x.second); cerr << '}';}
template<typename T>
void __print(const T &x) {int f = 0; cerr << '{'; for (auto &i: x) cerr << (f++ ? "," : ""), __print(i); cerr << "}";}
void _print() {cerr << "]\n";}
template <typename T, typename... V>
void _print(T t, V... v) {__print(t); if (sizeof...(v)) cerr << ", "; _print(v...);}
#ifndef ONLINE_JUDGE
#define debug(x...) cerr << "[" << #x << "] = ["; _print(x)
#else
#define debug(x...)
#endif
typedef long long ll;
typedef pair<int, int> pii;
int main() {
ios::sync_with_stdio(false); cin.tie(0);
int n, m, k;
cin >> n >> m >> k;
vector<int> a(n+1), b(m+1);
int a_sum = 0, a_min = 1e5, b_sum = 0;
for (int i = 1; i <= n; ++i) {
cin >> a[i];
a_sum += a[i];
a_min = min(a_min, a[i]);
}
for (int i = 1; i <= m; ++i) {
cin >> b[i];
b_sum += b[i];
}
if (a_min < k || b_sum < a_sum) {
cout << "Impossible\n";
return 0;
}
vector<int> pre(b_sum+1, -1e5), cur;
pre[0] = 0;
for (int i = 1; i <= m; ++i) {
cur.assign(b_sum+1, -1e5);
for (int h = 0; h <= b_sum; ++h) {
if (h < b[i]) {
cur[h] = pre[h];
} else {
cur[h] = max(pre[h], pre[h - b[i]] + min(b[i], n));
}
}
swap(pre, cur);
}
int ans = 1e9;
for (int h = a_sum; h <= b_sum; ++h) {
if (pre[h] >= n*k) {
ans = h - a_sum;
break;
}
}
if (ans == 1e9) {
cout << "Impossible\n";
} else {
cout << ans << '\n';
}
}
