#include <bits/stdc++.h>
using namespace std;
long int a[10000];
int main()
{
long int n,i;
while(cin>>n)
{
if(n==0) break;
a[1]=1;
a[2]=2;
for(i=3;i<=n;i++)
{
a[i]=a[i-1]+a[i-2];
}
cout<<a[n]<<'\n';
}
return 0;
}
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