17186.cpp

#include <bits/stdc++.h>
#define fastio ios_base::sync_with_stdio(0), cin.tie(0), cout.tie(0)

#define ll long long
using namespace std;

const ll INF = 1e9 + 7;
const ll DIV = 987654321;

int n,m, k;
int A[303], B[303];
int dp[101010];
int main()
{
    fastio;
    cin >> n >> m >> k;
    int tot = 0;
    for(int i =1 ;i <= n;i++) cin >> A[i], tot += A[i];
    for(int i = 1;i<=m;i++) cin >> B[i];
    for(int i = 1;i<=n;i++){
        if(A[i] < k){
            cout << "Impossible\n";
            return 0;
        }
    }    
    fill(dp, dp + 100011, -INF);
    dp[0]= 0;
     for(int i = 1;i<=m;i++){
        for(int j = 100000;j>0;j--){
            if(j >= B[i])
                dp[j] = max(dp[j], dp[j - B[i]]+min(B[i], n));
        }
    }
    for(int i = tot;i<=100000;i++){
        if(dp[i] >= n * k){
            cout << i - tot <<  "\n";
            return 0;
        }
    }
    cout << "Impossible\n";

    return 0;
}