Scope of variable within "with" statement?

I am reading only firstline from python using :

with open(file_path, 'r') as f:
    my_count = f.readline()
print(my_count)

I am bit confused over scope of variable my_count. Although prints work fine, would it be better to do something like my_count = 0 outside with statement first (for eg in C in used to do int my_count = 0)