3300 - 找规律（斐波那契数列）

<span style="font-family:宋体;">【问题描述】</span>

<span style="font-family:宋体;">找规律：根据下列规律找出第</span><span>N</span><span style="font-family:宋体;">个数是多少？</span><span> 1,2,3,5</span><span style="font-family:宋体;">……（</span><span>3&lt;=n&lt;=20</span><span style="font-family:宋体;">）</span>

<span></span>

<span style="font-family:宋体;">【输入格式】</span>

<span style="font-family:宋体;">一个正数数</span><span>n</span><span style="font-family:宋体;">（</span><span>3&lt;=n&lt;=20</span><span style="font-family:宋体;">）</span>

<span style="font-family:宋体;">【输出格式】</span>

<span style="font-family:宋体;">输出一个正整数</span><span> </span>

<span style="font-family:宋体;">【输入样例】</span>

<span>5</span>

<span style="font-family:宋体;">【输出样例】</span>

<span>8</span>

<span style="font-family:宋体;">【数据规模】</span>

<span>3&lt;=n&lt;=20</span>

<span style="font-family:宋体;">【时间限制】</span>

<span>1s</span>

Input

Output

Examples

Input

Output

Solution C++

#include<iostream>
using namespace std;
int a[1000];
int main()
{
	int n;
	cin>>n;
	a[1]=1;
	a[2]=2;
	for(int i=3;i<=n;++i)
	a[i]=a[i-1]+a[i-2];
	cout<<a[n];
}

Time Limit	1 second
Memory Limit	128 MB

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