#include <stdio.h>
#include <string.h>
#define Lmax 300

int A[Lmax], B[Lmax], C[Lmax];
int N, t, i;

void Add(int A[], int B[], int C[]) {
	int i, t, max;
	
	for (i = A[0] + 1; i <= B[0]; i++)
		A[i] = 0;
	for (i = B[0] + 1; i <= A[0]; i++)
		B[i] = 0;
	
	max = A[0] > B[0] ? A[0] : B[0];
	C[0] = max;
	for (i = 1, t = 0; i <= max; i++) {
		C[i] = (A[i] + B[i] + t) % 10;
		t = (A[i] + B[i] + t) / 10;
	}
	if (t) {
		C[0]++;
		C[C[0]] = t;
	}
}

void Atrib(int A[], int B[]) {
	memcpy(A, B, sizeof(int) * (B[0] + 1));
}

int main() {
	
	FILE *f = fopen("nunta.in", "r");
	FILE *g = fopen("nunta.out", "w");
	
	fscanf(f, "%d", &N);
	
	A[0] = A[1] = 1;
	B[0] = B[1] = 1;
	t = 2;
	
	while (t < N + 1) {
		Add(A, B, C);
		Atrib(A, B);
		Atrib(B, C);
		t++;
	}
	
	for (i = B[0]; i > 0; i--)
		fprintf(g, "%d", B[i]);
	
	fclose(f);
	fclose(g);
	
	return 0;
}