#include <bits/stdc++.h>
#define ll long long
#define to_str to_string
#define pb push_back
#define pp pop_back
using namespace std;
void code() {
int n, m, k; cin >> n >> m >> k;
if(m < k) {
cout << "Impossible";
return;
}
int sum = 0;
for(int i = 0; i < n; i++) {
int x; cin >> x;
sum+=x;
}
vector<int> a;
for(int i = 0; i < m; i++) {
int x; cin >> x;
a.pb(x);
}
if(k == 1) {
if(m == 1) {
if(a[0] >= sum) {
cout << a[0] - sum;
} else {
cout << "Impossible";
}
} else {
if(a[0] >= sum) cout << a[0] - sum;
else if(a[1] >= sum) cout << a[1] - sum;
else if(a[1] + a[0] >= sum) cout << a[1] + a[0] - sum;
else cout << "Impossible";
}
} else {
if(a[0] + a[1] >= sum) {
cout << a[0] + a[1] - sum;
} else {
cout << "Impossible";
}
}
}
int main()
{
ios_base::sync_with_stdio(false);
cout.tie(0);
cin.tie(0);
// freopen(".in", "r", stdin);
// freopen(".out", "w", stdout);
int t = 1;
// cin >> t;
for(int i = 0; i < t; i++) code();
return 0;
}
/*
/)/)~┏━━━━━━━━━━━━┓
(•-•)~ ♡ осторожно важный код ♡
/づづ~ ┗━━━━━━━━━━━━┛
*/
