View Code of Problem 23

#include <iostream>
#include <cstdio>
using namespace std;
int main(){
    int n,a[999];
    while(cin>>n&&n!=0){
        a[1]=1,a[2]=2;
        for(int i=3;i<=n;i++){
            a[i]=a[i-1]+a[i-2];
        }
        cout<<a[n]<<endl;
    }
    return 0;
}