题号：NC221565
时间限制：C/C++/Rust/Pascal 1秒，其他语言2秒
空间限制：C/C++/Rust/Pascal 256 M，其他语言512 M
Special Judge, 64bit IO Format: %lld
时间限制：C/C++/Rust/Pascal 1秒，其他语言2秒
空间限制：C/C++/Rust/Pascal 256 M，其他语言512 M
Special Judge, 64bit IO Format: %lld
题目描述
It is well known that Fibonacci sequence satisfies
Now, Willis wants to know the sum
Willis need to do the homework of real analysis, so he left this problem to you.
Now, Willis wants to know the sum
Willis need to do the homework of real analysis, so he left this problem to you.
输入描述:
A single integer(
).
输出描述:
The sum. You answer will considered correct if the absolute or relative error is less than
.