#include <bits/stdc++.h>
#define nl "\n"
#define no "NO"
#define yes "YES"
#define fi first
#define se second
#define vec vector
#define task "main"
#define _mp make_pair
#define ii pair<int, int>
#define sz(x) (int)x.size()
#define all(x) x.begin(), x.end()
#define evoid(val) return void(std::cout << val)
#define FOR(i, a, b) for(int i = (a); i <= (b); ++i)
#define FOD(i, b, a) for(int i = (b); i >= (a); --i)
#define unq(x) sort(all(x)); x.resize(unique(all(x)) - x.begin())
using namespace std;
template<typename U, typename V> bool maxi(U &a, V b) {
if (a < b) { a = b; return 1; } return 0;
}
template<typename U, typename V> bool mini(U &a, V b) {
if (a > b or a == -1) { a = b; return 1; } return 0;
}
const int N = (int)300 + 9;
const int mod = (int)1e9 + 7;
void prepare(); void main_code();
int main() {
ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);
if (fopen(task".inp", "r")) {
freopen(task".inp", "r", stdin);
freopen(task".out", "w", stdout);
}
const bool MULTITEST = 0; prepare();
int num_test = 1; if (MULTITEST) cin >> num_test;
while (num_test--) { main_code(); }
}
void prepare() {};
int a[N], b[N];
long long dp[2][N][N];
void main_code() {
int n, m, k; cin >> n >> m >> k;
for(int i = 1; i <= n; ++i) cin >> a[i];
for(int i = 1; i <= m; ++i) cin >> b[i];
memset(dp, -1, sizeof dp);
// build k tang
if (*min_element(a + 1, a + n + 1) < k)
evoid("Impossible");
long long s = 0;
FOR(i, 1, m) s += b[i];
FOR(i, 1, n) s -= a[i];
if (s < 0) evoid("Impossibe");
s = 0;
FOR(i, 1, n) s += a[i] - k;
memset(dp, -1, sizeof dp);
// sum thua nho
dp[0][0][0] = 0;
for(int c = 0; c < m; ++c) {
bool s = c & 1;
for(int layer = 0; layer < k; ++layer)
for(int r = 0; r <= n; ++r) if (dp[s][layer][r] != -1) {
long long &v = dp[s][layer][r];
mini(dp[s ^ 1][layer][r], v);
if (r == n) {
mini(dp[s ^ 1][layer + 1][0], v);
continue ;
}
// cerr << c << ' ' << layer << ' ' << r << ' ' << v << nl;
// neu pick chef c
// build duoc layer tang
if (r + b[c + 1] <= n) {
mini(dp[s ^ 1][layer][r + b[c + 1]], v);
} else if (b[c + 1] >= n) {
// build duoc the mot layer
mini(dp[s ^ 1][layer + 1][r], v + b[c + 1] - n);
} else {
mini(dp[s ^ 1][layer + 1][(r + b[c + 1]) % n], v);
}
v = -1;
}
}
long long ans = -1;
for(int r = 0; r <= n; ++r)
if (dp[m & 1][k][r] != -1) {
long long v = dp[m & 1][k][r] + r;
// cerr << k << ' ' << r << ' ' << v << nl;
if (v >= s)
mini(ans, v - s);
}
if (ans == -1)
evoid("Impossible");
cout << ans;
}
/* Let the river flows naturally */
