/* Author:Sepehr Mohammadi-mohamadi-sepehr.blog.ir */
#include <iostream>
using namespace std;
string Add(string, string);
int main()
{
    string f1 = "1", f2 = "0", temp;
    int i = 1;
    while (f1.length() < 1000)
    {
        temp = Add(f1,f2);
        f2 = f1;
        f1 = temp;
        i++;
    }
    cout<<i<<endl;
    system("Pause");
}
string Add(string p, string q)
{
    string answer = "";
    int digit1, digit2, result, carry = 0;

    if (q.length() > p.length())
    {
        int difference = q.length() - p.length();
        for(int i = 0; i < difference; i++)
            p = '0' + p;
    }
    if (q.length() < p.length())
    {
        int difference = p.length() - q.length();
        for(int i = 0; i < difference; i++)
            q = '0' + q;
    }
    for (int i = p.length() - 1; i >= 0; i--)
    {
        digit1 = int(p[i]) - 48;
        digit2 = int(q[i]) - 48;

        result = digit1 + digit2 + carry;
        if (result >= 10)
        {
            carry = result / 10;
            result = result % 10;
        }
        else
            carry = 0;
        answer = char(result + 48) + answer;
    }
    if (carry != 0)
        answer = char(carry + 48) + answer;

    return answer;
}
/* Author:Sepehr Mohammadi-mohamadi-sepehr.blog.ir */