#include<iostream> // cin\cout\endl #include<cstdio> //scanf()\printf() #include<cstring> // strcpy()\strcat()\strcmp()\strlen()\memset() #include<cmath> //sqrt()\pow()\abs()\ceil()\floor()\max()\min() using namespace std; int main(){ int x,y=1,yu=0; cin>>x; while(yu<x){ if(x%y==0){ yu+=y; } y++; } if(yu==x){ cout<<"YES"; } else{ cout<<"NO"; } return 0; }