1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
#include <iostream>
#include <vector>
#include <algorithm>
#include <string>
#include <math.h>

using namespace std;

int main() {

	ios_base::sync_with_stdio(0);

	long long sufix = -1,
	          sufix_temp = -1,
	          result = -1;

	cin >> sufix_temp;

	long long fibo_n0 = 0,
	          fibo_n1 = 1,
	          fibo_n2 = 0;

	sufix = sufix_temp;
	int digits = 0;
	while (sufix_temp != 0) {
		sufix_temp /= 10;
		++digits;
	}

	if (sufix == 0)
		result = 0;
	else if (sufix == 1)
		result = 1;
	else {
		// fibo 15*10^(n-1)
		long long modulo = pow(10, digits);
		long long max_count = 15 * pow(10, digits - 1);
		for (long long i = 0; i < max_count; ++i) {

			fibo_n2 = (fibo_n1 + fibo_n0) % modulo;
			if (fibo_n2 == sufix) {
				result = i + 2;
				break;
			}
			fibo_n0 = fibo_n1;
			fibo_n1 = fibo_n2;
		}
	}

	if (result >= 0)
		cout << result << endl;
	else
		cout << "NIE" << endl;

	return 0;
}