import sys

def stackQue(n,ls):
    if len(ls)!=n:
        return False     
    i=0
    while i<len(ls):
        tmpl=[c for c in ls[i:] if ls[i]>c]
        if not isSort(tmpl):
            return False
        i+=1
    return True

def isSort(ls,reverse=False):
    if not reverse:
        i=0
        while i<len(ls)-1:
            if ls[i]<ls[i+1]:
                return False
            i+=1
        return True
          
i = 0          
for line in sys.stdin:
    a = line.split()
    n = len(a)
    ls = map(lambda x:int(x),a)
    
    
    if n == 1 and ls[0]==1:
           i +=1
           if i%2 == 0:
               print 'Yes'

    if 1< n <= 100:      
            re = stackQue(n,ls)
            if re is True:
               print 'Yes'
            else:
               print 'No'
          
          
/**************************************************************
	Problem: 2119
	User: admin
	Language: Python
	Result: Wrong Answer
****************************************************************/