#include using namespace std; #define rep(i,n) for (int i = 0; i < (n); i++) #define REP(i,a,b) for(int i=(a);i<(b);i++) #define all(v) begin(v),end(v) #define fi first #define se second template inline bool chmax(A &a, B b) { if (a inline bool chmin(A &a, B b) { if (a>b) { a=b; return 1; } return 0; } using ll = long long; using pii = pair; using pll = pair; constexpr ll inf = 2e9; constexpr ll llinf = 9e18; //constexpr ll MOD = 998244353; constexpr ll MOD = 1000000007; const double pai=acos(-1); int main() { //cout<>a; REP(i,1,sqrt(a)){ ll b=i*(i+1)/2; if((a-b)%i==0){ cout<<"YES"<