#include <stdio.h>

#define fibsize 40
int fib[fibsize];


int main()
{
    int x;
    extern void initfib();
    initfib();
    while (scanf("%d", &x) == 1)
        printf("%d\n", fib[x]);
    return 0;
}


void initfib()
{
    int i;
    fib[1] = fib[2] = 1;
    for (i = 3; i < fibsize; i++)
        fib[i] = fib[i-1] + fib[i-2];
}