incdecseq

n=int(input())
l=list()
for i in range(n):
    l.append(int(input()))

def checkseq(n,l=[]):
    for i in range(n-1):
        if(l[i]>l[i+1]):
            pass
        else:
            break

    if l[i]==l[i+1]:
        i +=1

    for j in range(i,n-1):
        if(l[j]<l[j+1]):
            pass
        else:
            return False

    return True

print(checkseq(n,l))