#include //#include using namespace std; //using namespace atcoder; #define all(v) v.begin(),v.end() using ll = long long; using ull = unsigned long long; using lll = __int128; using vll=vector; using vvll = vector>; using P = pair; using vp=vector>; //using mint=modint1000000007; //using mint=modint998244353; const ll INF=1ll<<60; ll mod10=1e9+7; ll mod99=998244353; const double PI = acos(-1); #define rep(i,n) for (ll i=0;i=0;--i) #define rep2(i,a,n) for (ll i=a;i=n;--i) templatebool chmax(T &a, const T &b) { if (abool chmin(T &a, const T &b) { if (b>N; vll A(N);rep(i,N) cin>>A[i]; map mp; rep(i,N) mp[A[i]]++; sort(all(A)); ll ans=0; for(auto [a,b]:mp){ auto it=lower_bound(all(A),2*a); ans+=b*(b-1)*(it-A.begin()-b); } cout << ans/2 << endl; return 0; } int main(){ cin.tie(0); ios::sync_with_stdio(false); ll T=1;//cin>>T; rep(i,T) solve(); }