打表或推式子可得答案为斐波那契数列。

题目让我用递归我就递归？我这么没面子的吗？

线性的斐波那契太高级了，我们来个低级的打表。

#include<bits/stdc++.h>
using namespace std;

long long a[65] {0,1,2,3,5,8,13,21,34,55,89,144,233,377,610,987,1597,2584,4181,6765,10946,17711,28657,46368,75025,121393,196418,317811,514229,832040,1346269,2178309,3524578,5702887,9227465,14930352,24157817,39088169,63245986,102334155,165580141,267914296,433494437,701408733,1134903170,1836311903,2971215073,4807526976,7778742049,12586269025,20365011074,32951280099,53316291173,86267571272,139583862445,225851433717,365435296162,591286729879,956722026041,1548008755920,2504730781961};
int main() {
	int n;
	cin>>n;
	cout<<a[n];
	return 0;
}