#include <bits/stdc++.h>
#define printv(a, b) {\
for(auto pv : a) b << pv << " ";\
b << "\n";\
}
using namespace std;
typedef long long ll;
const ll MAX = INT_MAX;
void nosol(){
cout << "Impossible\n";
exit(0);
}
int n, m, k;
vector<int> a;
vector<int> b;
ll sa = 0;
const int SZ = 300;
int main(){
ios_base::sync_with_stdio(false);
cin.tie(0);
cerr.tie(0);
cin >> n >> m >> k;
a.resize(n + 1);
b.resize(m + 1);
ll sb = 0;
for(int i = 1; i <= n; i++) cin >> a[i], sa += a[i];
for(int i = 1; i <= m; i++) cin >> b[i], sb += b[i];
sort(a.begin() + 1, a.end(), greater<>());
sort(b.begin() + 1, b.end());
if(k > m || sa > sb){
nosol();
}
for(int i = 1; i <= n; i++) if(a[i] < k) nosol();
assert(k == 1);
vector<bool> dp(100001);
dp[0] = true;
for(int i = 1; i <= m; i++){
for(int j = 100000; j >= b[i]; j--){
if(dp[j - b[i]]) dp[j] = true;
}
}
for(int i = sa; i <= 100000; i++){
if(!dp[i]) continue;
cout << i - sa << "\n";
return 0;
}
return 0;
}
