#include <fstream>
#include <iostream>
// 999th Fibonacci number has 209 digits, by the way,
// so I'm '''rounding''' that to 300.
typedef int big_nr[300];
unsigned N;
big_nr first, sec;


// Adds two big numbers;
// Important: the result is stored in 'x'!!!!
void Add(big_nr x, big_nr y)
{
    unsigned t = 0;
    if (x[0] < y[0])
    {
        x[0] = y[0];
    }
    for (unsigned i = 1; i <= x[0]; ++i, t /= 10)
    {
        t = x[i] + y[i] + t;
        x[i] = t % 10;
    }
    if (t == 1)
    {
        x[++x[0]] = t;
    }
}


// Function that returns the 'q' Fibonacci number;
// it also works for Fibonacci numbers higher than 2^64 - 1.
unsigned big_fib(unsigned q)
{
    // initialise our 'big_nr's inside the 'big_fib' function, via
    // the 'initialise' function (via lambdas).
    auto initialise = []()
    {
        first[0] = sec[0] = 1;
        // Here, we define the first Fibonacci number to be 1,
        // and the second Fibonacci number to be 2.
        first[1] = 1, sec[1] = 2;
    };
    initialise();
    // Current index of the fib. nr.
    // The cases for q = 1 and q = 2 have (already) been solved.
    unsigned index = 2;
    while (index < q)
    {
        index += 2;
        Add(first, sec);
        Add(sec, first);
    }
    return index;
}


// Function that reads the input.
void read()
{
    std::ifstream fisierIN("nunta.in");
    fisierIN >> N;
    fisierIN.close();
}


// Function that displays the result (i.e. writes the
// result to the requested folder).
void display()
{
    unsigned val = big_fib(N);
    if (val == N)
    {
        std::ofstream fisierOUT("nunta.out");
        for (unsigned i = sec[0]; i >= 1; --i)
        {
            fisierOUT << sec[i];
        }
        fisierOUT.close();
    }
    else
    {
        std::ofstream fisierOUT("nunta.out");
        for (unsigned i = first[0]; i >= 1; --i)
        {
            fisierOUT << first[i];
        }
        fisierOUT.close();
    }
}


int main()
{
    read();
    display();
    return 0;
}