#include <cstdio>

using namespace std;

const int BASE = 10;
const int DIG = 209;

struct Huge {
  unsigned char v[DIG];
  Huge () {
    for (int i = 0; i < DIG; ++i)
      v[i] = 0;
  }
  Huge operator + (const Huge &other) const {
    Huge aux;
    int i, t = 0;
    for (i = 1; i <= v[0] || t; ++i, t /= BASE)
      aux.v[i] = (t += v[i] + other.v[i]) % BASE;
    aux.v[0] = i - 1;
    return aux;
  }
} a, b, c;

int main()
{
    int n, ind;
    fscanf(fopen("nunta.in", "r"), "%d", &n);
    a.v[0] = a.v[1] = ind = 1;
    b = c = a;
    for (int i = 1; i < n; ++i) {
      c = a + b;
      a = b; b = c;
    }
    FILE *fout = fopen("nunta.out", "w");
    for (int i = c.v[0]; i > 0; --i)
      fprintf(fout, "%d", c.v[i]);
    return 0;
}