Problem Description

Your objective for this question is to develop a program which will generate a fibbonacci number. The fibbonacci function is defined as such:

f(0) = 0

f(1) = 1

f(n) = f(n-1) + f(n-2)

Your program should be able to handle values of n in the range 0 to 50.

 

Input

Each test case consists of one integer n in a single line where 0≤n≤50. The input is terminated by -1.

 

Output

Print out the answer in a single line for each test case.

 

Sample Input

3

4

5

-1

 

Sample Output

2

3

5

 

代码：

#include 
       
        using namespace std;const int maxn=1e5+10;long long int f[maxn];int main(){    int n;    while(~scanf("%d",&n))    {        if(n==-1)            break;        for(int i=1; i<=50; i++)        {            if(i==1||i==2)                f[i]=1;            else            {                f[i]=f[i-1]+f[i-2];            }        }        printf("%lld\n",f[n]);    }    return 0;}