#include <stdint.h>
#include <inttypes.h>
#include <stdlib.h>
#include <stdio.h>

#define MAX 48

uint32_t
fib(int16_t x)
{
  int16_t i;
  uint32_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;
}

int32_t
cs2dd(int8_t *buf, int16_t len)
{
  int16_t i, f=1;
  int32_t tot=0;
  
  for (i=len-1; i>=0; i--) {
    buf[i] %= 16;
    tot += (buf[i] * f);
    f *= 10;
  }
  return tot;
}

int32_t
c2dd(int8_t *buf)
{
  int8_t  x;
  int16_t idx=0;
  
  while(1) {
    x = getchar();
    if ((x > 47 && x < 58) == 0) break;
    buf[idx++] = x;
  }
  if (idx == 0) exit(0);

  return cs2dd(buf, idx);
}

int
main() {
  int8_t   buf[80];
  int16_t  x;
  uint32_t ret;

  while(1) {
    x = (int16_t)c2dd(buf);
    if ((x < MAX && x > -1) == 0) {
      printf("-1");
    } else {
      ret = fib(x);
      printf("%"PRIu32, ret);
    }
    printf("\n");
  }
  return 0;
}