Solve the programming task below in a Python markdown code block.
Read problems statements in Mandarin Chinese, Russian and Vietnamese as well. 

Compute:
floor[1*e] + floor[2*e] + floor[3*e] + ... + floor[n*e],
where floor[x] is the largest integer that is not greater than x, and e is Euler's number: 2.7182818284...

------ Input ------ 

A single line which contains a single integer: n.

------ Output ------ 

A single line which contains a single integer which should be the answer.

------ Constraints ------ 

1 ≤ n ≤ 10^{4000}

------ Subtasks ------ 

$Subtask #1 (50 points): 1 ≤ n ≤ 10^{100}
$$Subtask #2 (50 points): Original constraints.$

----- Sample Input 1 ------ 
3
----- Sample Output 1 ------ 
15
----- explanation 1 ------ 

floor[1*e] = floor[2.71828..] = 2.
floor[2*e] = floor[5.43656..] = 5.
floor[3*e] = floor[8.15484..] = 8.
So the answer is 2+5+8=15.

Note
Source code limit is 1000 bytes.