#include<bits/stdc++.h>
using namespace std;

#define fastkor ios_base::sync_with_stdio(false),cin.tie(0),cout.tie(0)
#define endl '\n'
#define ll long long

#define dvect vector<int>vect
#define pb(x) push_back(x)
#define vectinL(n) for(ll i=0;i<n;i++){ ll x; cin >> x; vect.push_back(x);}
#define vectin(n) for(int i=0;i<n;i++){ int x; cin >> x; vect.push_back(x);}
#define vectout(v) for(auto p: v) cout<<p<<" "; cout<<endl;
#define sortkor(x) sort(x.begin(),x.end())
#define reversekor(x) reverse(x.begin(),x.end())
#define all(vect) vect.begin(),vect.end()
#define mini_pos(a)    ( min_element((a).begin(), (a).end()) - (a).begin())
#define maxi_pos(a)    ( max_element((a).begin(), (a).end()) - (a).begin())

#define F first
#define S second
#define gcd(a,b) __gcd(a,b)
#define YES1 cout<<"Case "<<case++<<": YES\n"
#define NO1 cout<<"Case "<<case++<<": NO\n"
#define precision(n) fixed<<setprecision(n)
#define testcase ll t; cin >>t; while(t--)

#define yes cout<<"yes\n";
#define Yes cout<<"Yes\n";
#define YES cout<<"YES\n"

#define no cout<<"no\n";
#define No cout<<"No\n";
#define NO cout<<"NO\n"
#define vectd  vector<ll>vect(n)
const int N=2e5+10;
vector<pair<int,int>>moves=
{
    {-1,0},{1,0},{0,-1},{0,1}
};
const int mod=1e9+7;
ll fact[N+10];
vector<bool>isprime;
vector<int>primegula;
map<int,int>mp;
template <typename T>
inline void operator>>(istream &istream, vector<T> &v)
{
    for (T &i : v)
    {
        cin >> i;
    }
}

int main()
{
    fastkor;
   ll n;
   cin >> n;
   if(n<=50)
    YES;
   else
    NO;
}