#include <bits/stdc++.h>
using namespace std;
const int maxn = 305;
const int maxsum = maxn * maxn;
const int inf = 1e9;
int n, m, k;
int a[maxn];
int b[maxn];
int dp[maxn][maxsum];
void fastIO()
{
ios_base::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
}
int main()
{
fastIO();
cin >> n >> m >> k;
for (int i = 1; i <= n; ++i)
{
cin >> 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" << endl;
return 0;
}
}
for (int i = 0; i < maxn; ++i)
{
for (int j = 0; j < maxsum; ++j)
{
dp[i][j] = -inf;
}
}
int sumB = 0;
for (int i = 1; i <= m; ++i)
{
sumB += b[i];
}
int sumA = 0;
for (int i = 1; i <= n; ++i)
{
sumA += a[i];
}
if (sumA > sumB)
{
cout << "Impossible" << endl;
return 0;
}
dp[0][0] = 0;
for (int pos = 1; pos <= m; ++pos)
{
for (int sum = 0; sum <= sumB; ++sum)
{
dp[pos][sum] = dp[pos - 1][sum];
if (sum >= b[pos])
{
dp[pos][sum] = max(dp[pos][sum], min(b[pos], n) + dp[pos - 1][sum - b[pos]]);
}
}
}
for (int i = sumA; i <= sumB; ++i)
{
if (dp[m][i] >= n * k)
{
cout << i - sumA << endl;
return 0;
}
}
cout << "Impossible" << endl;
return 0;
}
