A.Fibonacci

#include<bits/stdc++.h>

using namespace std;

int fib[20];

int main(){
  ios::sync_with_stdio(false);
  // freopen("in.in", "r", stdin);
  fib[0] = 0;
  fib[1] = 1;
  for(int i=2; i<20; i++)
    fib[i] = fib[i-1] + fib[i-2];
  int n=0;
  while(cin >> n){
    if(n<20)
      cout << fib[n] << endl;
    else{
      double num = -0.5*log10(5.0) + n*log10((1.0+sqrt(5.0))/2.0);
      num -= (int)num;
      num = pow(10, num);
      while(num < 1000)
        num *= 10;
      cout << (int)num << endl;
    }
  }
  return 0;
}