#include <stdio.h>

unsigned long long
fib(unsigned n)
{
    unsigned long long fibs[] = {1, 1};
    unsigned long long t;

    for (; n > 1; --n) {
        t = fibs[0];
        fibs[0] = fibs[1];
        fibs[1] += t;
    }

    return fibs[1];
}

int main(void)
{
    int i;

    for (i = 0; i <= 10; ++i)
        printf("%d: %llu\n", i, fib(i));

    return 0;
}