Problems
Degree of two
Degree of two
n degrees of number 2 are written sequentially in a line, i.e. the numbers from 2 to 2n
without spaces. Find the value of n.
Input
n (1 ≤ n ≤ 1000) degrees of number 2 are written sequentially in a line.
Output
Print the value of n.
Input example #1
248163264128
Output example #1
7