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

long long unsigned fib(long long unsigned n)
{
   if ( n == 0 )
      return 0;
   else if ( n == 1 )
      return 1;
   else
      return (fib(n-1) + fib(n-2));
} 

int main (int argv, char **argc)
{
	long long unsigned i;
	long long unsigned x;

	if (argv != 2)
	{
		printf("Please, insert a number after name of file\n");
		return (0);
	}
	i = 0;

	while (argc[1][i] != '\0')
	{
		if (!(argc[1][i] >= '0' && argc[1][i] <= '9'))
		{
			printf("Please, insert a number of digits\n");
			return (0);
		}
		i++;
	}

	x = atoll(argc[1]);
	if (x < 1 || x > 4611686018427387904)
	{
		printf("Please, insert a number between 1 and 2^62\n");
		return (0);
	}
	i = x / 2;
	while (fib(i) >= x)
		i = i / 2;
	if (fib(i) == x)
		{
			printf("%llu\n", i - 1);
			return (0);
		}
	while (fib(i) < x)
		i++;
	printf("%llu\n", i - 1);
	return (0);
}