'''
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 index of the first term in the Fibonacci sequence to contain 1000 digits?
'''

# Initializing values
a = 1
b = 2
c = a + b
ind = 4

# Stopping counting when the first term in the Fibonacci sequence hits 1000 digits
while len(str(c)) < 1000:
	a = b
	b = c
	c = a + b
	ind += 1

print(ind)
