if statement between values of two pandas Dataframes

I want to make an if statement with the values of two pandas data frames (the values I want to compare are in column 0):

EDIT:

First of all I wanted to check the number of times at which the value of df1 is greater than the value of df2.

for row in df1:
    if df1[0] > df2[0]:
       Print('Ok')
    else:
       Print('not OK')

and what I get is:

ValueError: The truth value of a Series is ambiguous. Use a.empty, a.bool(), a.item(), a.any() or a.all().