Quicker way of finding the Sub sequence values

subsequence.py

a = "abcdefg"
l = ["a", "acef", "defg", "gg"]

word_count = 0

for word in l:
    i = 0  # pointer in main string
    for ch in word:
        i = a.find(ch, i)
        if i == -1:
            break
        i += 1
    else:
        word_count += 1

print(word_count)