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

Hint

Note:

 

you can use 64bit integer: __int64

#include <iostream>

using namespace std;

const int limit = 51;

_int64 fib[limit];

int main()

{

    int num;

    fib[0] = 0;

    fib[1] = 1;

    for (int i = 2; i <= limit; i++)

    {

        fib[i] = fib[i - 1] + fib[i - 2];

    }

    while (cin >> num && num!=-1)

    {

        cout << fib[num] << endl;

    }

    return 0;

}