#include using namespace std; using ll = long long; using ull = unsigned long long; #define rep(i,a) for(int i=0;i<(a);i++) #define MOD 1000000007 int main(){ ll n; cin>>n; for(ll i=1;i<60*60*24;i++){ ll num=i*(i+1)/2; if(num>=n){ cout<<"YES"<