import math
from decimal import *

getcontext().prec = 102
sqrt_2 = Decimal(2).sqrt()

def solution(s):
    total = 0
    for i in range(int(s)+1):
        total += int(math.floor(i*sqrt_2))
        #print i, total
    return str(total)

def check_known_pattern(start, end, memo):
    if '0'*(end-start+1) in memo: # TODO: checkk value in the memo
        return '0'*(end-start+1)
    return False

def generate_dfs(start, end, memo):
    pattern = check_known_pattern(start, end, memo)
    if pattern:
        yield pattern, memo[pattern]
    else:
        new_pattern = ''
        new_value = 0 # TODO: calculate new_value
        pivot = int(math.floor((start+end)/2)) # TODO: power of 2 is optimal
        for pattern, value in generate_dfs(start, pivot, memo):
            new_pattern += pattern
            new_value += value
            yield pattern, value
        for pattern, value in generate_dfs(pivot + 1, end, memo):
            new_pattern += pattern
            new_value += value
            yield pattern, value
        memo[new_pattern] = new_value

memo = {'0': 1, '1': 1} # TODO: upgrade memo
total = 0
for pattern, value in generate_dfs(1, 5, memo):
    total += value
    print pattern, value
print total, memo

exit(0)



tests = [
        ['77', '4208'],
        ['1', '1'],
        ['2', '3'],
        ['3', '7'],
        ['4', '12'],
        ['5', '19'],
        ['6', '27'],
        ['7', '36'],
        ['8', '47'],
        ['9', '59'],
        ['10', '73'],
        ]


for test in tests:
    result = solution(test[0])
    print(test[0], result == test[1], result, test[1])