#include <bits/stdc++.h>
typedef long long ll;
using namespace std;
#define FOR(i, x, y) for(ll i=x; i<y; i++)
#define FORNEG(i, x, y) for(ll i=x; i>y; i--)
#define fast() ios_base::sync_with_stdio(false);cin.tie(NULL)
ll n,m,k;
ll dp[301][90001];
ll meal[301];
ll chefs[301];
ll sum = 0;
ll sum2 = 0;
int main(){
FOR(i,0,301) FOR(j,0,90001) dp[i][j] = -1;
cin >> n >> m >> k;
FOR(i,0,n){
cin >> meal[i];
sum += meal[i];
}
FOR(i,0,m){
cin >> chefs[i];
sum2 += chefs[i];
}
FOR(i,0,n){
if (meal[i] < k){
cout << "Impossible";
return 0;
}
}
ll temp = 0;
FOR(i,0,m){
temp += min(n, chefs[i]);
}
if (temp < n*k){
cout << "Impossible";
return 0;
}
if (sum > sum2){
cout << "Impossible";
return 0;
}
dp[0][0] = 0;
FOR(i,0,m){
FOR(j,0,90001){
if (dp[i][j] == -1) continue;
if (dp[i+1][j+chefs[i]] == -1){
dp[i+1][j+chefs[i]] = min(n, chefs[i]) + dp[i][j];
}else{
dp[i+1][j+chefs[i]] = max(dp[i+1][j+chefs[i]], min(n, chefs[i]) + dp[i][j]);
}
dp[i+1][j] = max(dp[i][j], dp[i+1][j]);
}
}
ll ans = 100000000000;
FOR(i,0,301) FOR(j,0,90001){
if (dp[i][j] == -1) continue;
if (dp[i][j] < n*k) continue;
if (j<sum) continue;
ans = min(ans, j-sum);
}
cout << ans << endl;
}
