#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define fi first
#define se second
#define pb push_back
#define vi vector<int>
#define vl vector<ll>
#define pi pair<int, int>
#define pl pair<ll,ll>
#define all(x) (x).begin(),(x).end()
int main() {
ios::sync_with_stdio(0);
cin.tie(0);
int n,m,k;
cin >> n >> m >> k;
vi a(n);
vi b(m);
for (int i=0; i<n; i++) {
cin >> a[i];
}
for (int i=0; i<m; i++) {
cin >> b[i];
}
int s=accumulate(all(b),0);
int s2=accumulate(all(a),0);
if (*min_element(all(a))<k || m<k || s<s2) {
cout << "Impossible\n";
return 0;
}
int dp[m+1][s+1];
memset(dp,0,sizeof(dp));
for (int i=0; i<m; i++) {
for (int j=0; j<=s; j++) {
dp[i+1][j]=max(dp[i+1][j],dp[i][j]);
if (j+b[i]<=s) {
dp[i+1][j+b[i]]=max(dp[i+1][j+b[i]],dp[i][j]+min(n,b[i]));
}
}
}
int ans=1e9;
for (int j=s2; j<=s; j++) {
if (dp[m][j]>=n*k) {
ans=min(ans,j-s2);
}
}
if (ans==1e9) {
cout << "Impossible\n";
}
else {
cout << ans << '\n';
}
return 0;
}
