#include <cstdio>
#include <cstring>

using namespace std;

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

unsigned char a[DIG], b[DIG], c[DIG];

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