RosettaCodeData/Task/Fibonacci-sequence/Aime/fibonacci-sequence.aime

integer
fibs(integer n)
{
    integer w;

    if (n == 0) {
        w = 0;
    } elif (n == 1) {
        w = 1;
    } else {
        integer a, b, i;

        i = 1;
        a = 0;
        b = 1;
        while (i < n) {
            w = a + b;
            a = b;
            b = w;
            i += 1;
        }
    }

    return w;
}