#include <iostream>
#include <algorithm>
using namespace std;
const int nmax = 305;
int dp[2][nmax * nmax];
int b[nmax];
int main()
{
///bagi artificial o singura data un chef la o anumita mancarica ca te int doar ca suma timp chefi >= suma timpi mancare dupa
///=> un chef contribuie la min(n, bi) mancarici
///tb n*k in total minim
///dp[x] = x ore chefi ; contributie artificiala
///dp[i][x] -> primii i chefi x ore => dp[i+1][x] = dp[i][x] (nu te int) + dp[i][x - b[i + 1]] => 0/1 dp
int A, a, n, m, k, i, j, B;
cin >> n >> m >> k;
A = B = 0;
for (i = 1; i <= n; i++)
{
cin >> a; A += a;
if (a < k)
{
cout << "Impossible";
return 0;
}
}
for (j = 1; j <= m; j++)
cin >> b[j], B += b[j];
for (i = 0; i <= 1; i++)
for (j = 0; j <= B; j++)
dp[i][j] = -2e9;
dp[0][0] = 0;
dp[1][0] = 0;
sort(b + 1, b + m + 1);
reverse(b + 1, b + m + 1);
for (i = 1; i <= m; i++)
for (j = b[i]; j <= B; j++)
dp[i % 2][j] = max(dp[1 - i % 2][j - b[i]] + min(b[i], n), dp[1 - i % 2][j]);
for (i = A; i <= B; i++)
if (dp[m % 2][i] >= n * k)
{
cout << i - A;
return 0;
}
cout << "Impossible";
return 0;
return 0;
}
