#include <bits/stdc++.h>
using namespace std;
#pragma GCC optimize("O3")
#pragma GCC optimize("Ofast")
#pragma GCC target("avx2,popcnt")
//#define int long long
#define forn(i,n) for(int i=0;i<n;++i)
#define pb push_back
#define all(x) x.begin(),x.end()
#define rall(x) x.rbegin(),x.rend()
#define f first
#define s second
#define pi pair<int,int>
#define vii(a,n) vector<int>a(n);forn(i,n)cin>>a[i];
const int inf = 1e9;
const int mod = 998244353;
void imp() {
cout<<"Impossible";
exit(0);
}
const int S=9e4;
const int M=300;
bitset<S+1> dp[M+1];
void solve() {
int n,m,k; cin>>n>>m>>k;
vii(a,n);
vii(b,m);
int s=0, s2=0;
for(auto&x:a) s+=x;
for(auto&x:b) s2+=x;
if (s2<s) {
imp();
}
forn(i,n) if (a[i]<k) imp();
if (m<k) imp();
dp[0][0]=1;
sort(all(b));
for(auto&x:b) {
if (x<n) {
for (int i=s2-x; i>=0; --i) {
int j1=min(i/n,m);
int j2=min((i+x)/n,m);
if (dp[j1][i]) dp[j2][i+x]=1;
}
} else {
for (int j=m-1; j>=0; --j) {
dp[j+1]|=dp[j]<<x;
}
}
}
for (int i=s; i<=s2; ++i) {
for (int j=k; j<=m; ++j) {
if (dp[j][i]) {
cout<<i-s<<'\n';
return;
}
}
}
imp();
}
int32_t main() {
ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
solve();
}
