#include <iostream>
#include <bitset>
#include <algorithm>
using namespace std;
const int N = 305, NN = 90005;
bitset<90005> bt[N], Bt;
int a[N], b[N];
int main(){
int n, m, k, Ans = NN, ex = 0;
cin>>n>>m>>k;
for (int i=1;i<=n;i++)
cin>>a[i];
for (int j=1;j<=m;j++)
cin>>b[j];
sort(b + 1, b + m + 1);
for (int i=1;i<=n;i++){
if (a[i] < k)
return cout<<"Impossible\n", 0;
ex += a[i] - k;
}
Bt[0] = bt[0][0] = 1;
for (int i=1;b[i] < n;i++)
Bt |= Bt << b[i];
for (int i=m;b[i] >= n;i--){
for (int j=min(m - i + 1, k);j>=1;j--)
bt[j] |= (bt[j-1] << (b[i] - n)) | (bt[j] << b[i]);
}
for (int i=k;i>=0;i--){
for (int j=NN-1, l = 0;j>=0;j--){
while (j >= 0 and bt[i][j] == 0)
j--;
while (j >= 0 and l < N and (Bt[l] == 0 or j + l < ex))
l++;
if (j >= 0 and l < N)
Ans = min(Ans, j + l - ex);
}
Bt >>= n;
}
if (Ans == NN)
cout<<"Impossible\n";
else
cout<<Ans<<'\n';
}
