#include <iostream>
#include <iomanip>

using namespace std;

long Fib(unsigned int n);

int main() {
   int i;

   for(i =1; i < 21; i++) {
      cout << setw(2) << i << setw(20) << Fib(i) << endl;
   }

   return 0;
}


long Fib(unsigned int n){
   long f = 1;
   long prev =1, last =1;


   //        last     prev
   // F(n) = F(n-1) + F(n-2)
   unsigned int i;

   for(i = 2; i < n; i++) {
       f = last+prev;
       prev = last;
       last = f;
   }

   return f;
}