#include <stdio.h>

int Fibonacci(int n) {
    if (n == 0) {
        return 0;
    }
    else if (n == 1) {
        return 1;
    }
    return Fibonacci(n - 1) + Fibonacci(n - 2);
}

int main(void) {
    int n = 0;
    scanf("%d", &n);

    printf("%d\n", Fibonacci(n));
    return 0;
}