给定一个字母表和一个单词，找出单词中第一个出现在字母表中的字母。


Alphabet: a, b, c, d, e, f, g, h, i, j, k, l, m, n, o, p, q, r, s, t, u, v, w, x, y, z
Word: supercalifragilisticexpialidocious
The first letter in the word "supercalifragilisticexpialidocious" that appears in the alphabet is "a".