import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.util.*;
public class C {
public static void main(String[] args) throws IOException {
MyScanner sc = new MyScanner(System.in);
String p = sc.next();
int[] ds = new int[20000];
for(int i=0; i
=1) {
ds[i+1]--;
} else {
System.out.println("No");
return;
}
} else {
System.out.println("No");
return;
}
}
}
static class MyScanner
{
BufferedReader br;
StringTokenizer st;
public MyScanner(InputStream s)
{
br=new BufferedReader(new InputStreamReader(s));
}
public String nextLine() throws IOException
{
return br.readLine();
}
public String next() throws IOException
{
while(st==null || !st.hasMoreTokens())
st=new StringTokenizer(br.readLine());
return st.nextToken();
}
public int nextInt() throws IOException
{
return Integer.parseInt(next());
}
public double nextDouble() throws IOException
{
return Double.parseDouble(next());
}
public boolean ready() throws IOException
{
return br.ready();
}
public long nextLong() throws IOException
{
return Long.parseLong(next());
}
}
}