Project Euler#25 1000-digit Fibonacci number

#The Fibonacci sequence is defined by the recurrence relation:

#    Fn = Fn−1 + Fn−2, where F1 = 1 and F2 = 1.

#Hence the first 12 terms will be:

#    F1 = 1
#    F2 = 1
#    F3 = 2
#    F4 = 3
#    F5 = 5
#    F6 = 8
#    F7 = 13
#    F8 = 21
#    F9 = 34
#    F10 = 55
#    F11 = 89
#    F12 = 144

#The 12th term, F12, is the first term to contain three digits.

#What is the first term in the Fibonacci sequence to contain 1000 digits?

def fib(n):
    """assumes x an int >= 0
      returns Fibonacci of x"""
    a, b = 0, 1
    for i in range(n):
        a, b = b, a + b
    return a

i = 1
while True:
        temp = str(fib(i))
        if len(temp) >= 1000:
                break
        i += 1
print i