#include<bits/stdc++.h>

using namespace std;

#include<ext/pb_ds/assoc_container.hpp>
#include<ext/pb_ds/tree_policy.hpp>

using namespace __gnu_pbds;
#define ordered_set tree<int, null_type, less<int>, rb_tree_tag, tree_order_statistics_node_update>

#define   ll          long long
#define   pb          push_back
#define   F           first
#define   S           second
#define   pII         pair<ll, ll>
#define   all(v)      v.begin(),v.end()
#define   allr(v)     v.rbegin(),v.rend()
#define   Endl        "\n"
#define   Case()      cout<<"Case "<<++cs<<": "
#define   bug(a)      cerr<<#a<<" : "<<a<<endl
#define   Tc()        ll T, cs=0; cin>>T; hell:  while(T--)
#define   Tanmoy      ios_base::sync_with_stdio(false);cin.tie(0),cout.tie(0)

const ll Mod=1e9+7, MAX=1e6+10, SZ=2e5+5, N=1e13;
ll a[MAX], b[MAX];

int fx8[]={1, -1, 0, 0, 1, 1, -1, -1};
int fy8[]={0, 0, 1, -1, 1, -1, 1, -1};
int fx4[]={1, -1, 0, 0};
int fy4[]={0, 0, 1, -1};


int main()
{

     Tanmoy;
     ///  freopen("in.txt", "r", stdin);




         int n, m, ans=0, sum=0;

         cin>>n;
         if(n<=50){
            cout<<"YES\n";
         }
         else{
             cout<<"NO\n";
         }

    return 0;
}