#include <stdint.h>
#include <inttypes.h>
#include <stdlib.h>
#include "../cprintf.h"

#define MAX 47

uint32_t
fib(int16_t x)
{
  int16_t i;
  int32_t prev0, prev1, result;

  if (x == 0) return 0;

  prev0 = 0;
  prev1 = 1;
  result = prev1;

  for (i=2; i<x; i++) {
    prev0 = prev1;
    prev1 = result;
    result = prev0 + prev1;
  }
  return result;
}

int16_t
exp(int16_t base, int16_t exp)
{
  int16_t i, ret=1;
  
  for (i=0; i<exp; i++)
    ret *= base;

  return ret;
}

int16_t
read()
{
  char x, stack[5];
  int16_t i, idx=0, ret=0;
  
  while(1) {
    x = cgetc();
    if (x <= 47) break;
    if (x >= 58) break;
    stack[idx] = x;
    idx++;
  }
  if (idx == 0) exit(0);

  for (i=0; i<idx; i++) {
    stack[i] -= 48;
    stack[i] *= exp(10, idx-i-1);
    ret += stack[i];
  }
  cprintf("%"PRIu16"\n", ret);
  
  return ret;
}

int
main() {
  int16_t  x;
  uint32_t ret;

  while(1) {
    x = read();
    if (x > MAX) cprintf("-1\n");
    else {
      ret = fib(x);
      cprintf("%"PRIu32"\n", ret);
    }
  }
  return 0;
}