#include <stdio.h>
void main()
{
  int i,a[100],k,count,key,n,j,b[100];
  scanf("%d",&n);
  while(n!=0)
  {
    k=key=0;
    for(i=0;i<n;i++)
      scanf("%d",&a[i]);
    for(i=0;i<n;i++)
    {
		count=0;
      for(j=i+1;j<n;j++)
      {
        if(a[j]<a[i])
        {b[count]=a[j];
         count++;}
      }
      for(k=0;k<count-1;k++)
      {
        if(b[k]<b[k+1])
        key=1;
      }
    }
    if(key==0)
      printf("Yes\n");
	else
		printf("No\n");
     scanf("%d",&n);
  }
}
/**************************************************************
	Problem: 2119
	User: admin
	Language: C
	Result: Accepted
	Time:10 ms
	Memory:1144 kb
****************************************************************/