#include <bits/stdc++.h>

using namespace std;

int main()
{
    char A;
    cin >> A;
    if (A >= '0' && A <= '9') {
        cout << "YES";
    }   
    else {
        cout << "NO";
    }
    return 0;
}

Code C++:

#include <bits/stdc++.h>
using namespace std;
string s;
int d=0;
int main()
{
  cin>>s;
   if (s>="0" && s<="9") {
     cout<<"YES";
     d=1;
   }
   if (d==0) cout<<"NO";
}

Code Pascal:
var s:ansistring;
d:int64;
begin 
  read(s);
   if s[1] in ['0'..'9'] then d:=1;
   if d=1 then writeln('YES')
   else write('NO');
  end.

//nguyenanh21811 vẫn ggwp and comeback =))