constexpr bool isDebugMode = false; int testcase = 1; #include #if __has_include() #include using namespace atcoder; #endif using namespace std; typedef long long ll; typedef pair P; struct edge{long long to,cost;}; const int inf = 1 << 27; const long long INF = 1LL << 60; const int COMBMAX = 1001001; const long long MOD = 1000000007; //998244353; const long long dy[] = {-1, 0, 0, 1}; const long long dx[] = {0, -1, 1, 0}; const string abc = "abcdefghijklmnopqrstuvwxyz"; #define rep(i, n) for(int i = 0; i < (n); ++i) #define eachdo(v, e) for (const auto &e : (v)) #define all(v) (v).begin(), (v).end() #define lower_index(v, e) (long long)distance((v).begin(), lower_bound((v).begin(), (v).end(), e)) #define upper_index(v, e) (long long)distance((v).begin(), upper_bound((v).begin(), (v).end(), e)) long long mpow(long long a, long long n, long long mod = MOD){long long res = 1; while(n > 0){if(n & 1)res = res * a % mod; a = a * a % mod; n >>= 1;} return res;} void pt(){cout << endl; return;} template void pt(Head&& head){cout << head; pt(); return;} template void pt(Head&& head, Tail&&... tail){cout << head << " "; pt(forward(tail)...);} void dpt(){if(!isDebugMode) return; cout << endl; return;} template void dpt(Head&& head){if(!isDebugMode) return; cout << head; pt(); return;} template void dpt(Head&& head, Tail&&... tail){if(!isDebugMode) return; cout << head << " "; pt(forward(tail)...);} template void enu(T v){rep(i, v.size()) cout << v[i] << " " ; cout << endl;} template void enu2(T v){rep(i, v.size()){rep(j, v[i].size()) cout << v[i][j] << " " ; cout << endl;}} template void debug(T v){if(!isDebugMode) return; rep(i, v.size()) cout << v[i] << " " ; cout << endl;} template void debug2(T v){if(!isDebugMode) return; rep(i, v.size()){rep(j, v[i].size()) cout << v[i][j] << " " ; cout << endl;}} template inline bool chmin(T1 &a, T2 b){if(a > b){a = b; return true;} return false;} template inline bool chmax(T1 &a, T2 b){if(a < b){a = b; return true;} return false;} template long long recgcd(T1 a, T2 b){return a % b ? recgcd(b, a % b) : b;} bool valid(long long H, long long W, long long h, long long w) { return 0 <= h && h < H && 0 <= w && w < W; } void solve(); int main(){ cin.tie(nullptr); ios::sync_with_stdio(false); cout << fixed << setprecision(15); // cin >> testcase; while(testcase--) solve(); return 0; } void solve(){ ll N, M, C; cin >> N >> M >> C; vector a(N); rep(i, N) cin >> a[i]; vector b(M); rep(i, M) cin >> b[i]; sort(all(b)); double ans = 0; rep(i, N){ ll num = (M - upper_index(b, C / a[i])); ans += (double)num / (N * M); } pt(ans); }