program;
uses crt;
var a:longint;
begin
clrscr;
write('nhap a:');readln(a);
if(a>=0)and(a<=50)then write('n nam trong khoang tu 1 den 50')
else write('n khong nam trong khoang tu 1 den 50');
readln;
#include <bits/stdc++.h>
using namespace std;
int a;
int main()
{
cin>>a;
if ((a>=1) and (a<=50)) cout<<"YES";
else cout<<"NO";
return 0;
}