descr=%{
    The Fibonacci sequence is defined by the recurrence relation:

    F_(n) = F_(n−1) + F_(n−2), where F_(1) = 1 and F_(2) = 1.

    Hence the first 12 terms will be:

    F_(1) = 1
    F_(2) = 1
    F_(3) = 2
    F_(4) = 3
    F_(5) = 5
    F_(6) = 8
    F_(7) = 13
    F_(8) = 21
    F_(9) = 34
    F_(10) = 55
    F_(11) = 89
    F_(12) = 144

    The 12th term, F_(12), is the first term to contain three digits.

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

n=3
i=1
j=1
f=i+j
while f.to_s.length<1000
# while n<5
    n+=1
    i=j
    j=f
    f=i+j
    # puts %{#{n}, #{f}}
end
puts n