#!/usr/bin/pypy import math # calculate the length-l prefix of 2^n def prefix_power2(n,l): log = math.log10(2)*n declog = log - math.floor(log) return math.floor(pow(10,declog+l-1)) def main(): i = 0 count = 0 while count < 678910: i = i + 1 if prefix_power2(i, 3) == 123: count = count + 1 if count % 1000 == 0: print("p({},{})={}".format(123,count,i)) print("p({},{})={}".format(123,count,i)) if __name__ == "__main__": main()