#include <iostream>
using namespace std;
int febo(int x)
{
if (x==1)
return 1;
else if (x==2)
return 1;
else
return febo(x-1) + febo(x-2);
}
int main() {
// your code goes here
int n;
cin>>n;
cout<<febo(n) ;
return 0;
}
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