#include <stdio.h>
#include <string.h>

int Z[2][2], N, M[2];


void multMZ(){
    int a = M[0]*Z[0][0] + M[1]*Z[0][1];
    int b = M[0]*Z[1][0] + M[1]*Z[1][1];
    M[0] = a;
    M[1] = b;
}

int fib(int N, int i){
    multMZ();
    if(i != N)
        return fib(N, i+1);
    return M[1];
}

int main()
{
	freopen("kfib.in", "r", stdin);
	freopen("kfib.out", "w", stdout);
    Z[0][0] = 0;
    Z[0][1] = 1;
    Z[1][1] = 1;    
    Z[1][0] = 1;
    M[0] = 0; M[1] = 1;
	scanf("%d", &N);
    printf("%d", fib(N, 2));
}