result = 1
def search(a,i,x,y,z):
global result
if len(a) <= 1:
return 1
if i == 0:
x = min(a)-1
y = a[0]
z = max(a)+1
if 2*i + 1 < len(a):
if (a[2*i+1] < y) and (a[2*i+1] > x):
result = search(a,2*i+1,x,a[2*i+1],a[i]) * result
else:
return 0
if 2*i + 2 < len(a):
if (a[2*i+2] < z) and (a[2*i+2] > y):
return search(a,2*i+2,a[i],a[2*i+2],z) * result
else:
return 0
return 1
temp = input()
try:
if (search(list(map(int,(temp.split(',')))),0,None,None,None)) == 1:
print(True)
else:
print(False)
except:
print(True)