from collections import Counter

p1 = int(input())
p2 = int(input())
n = int(input())
r = []
ans = 0
for _ in range(n):
    r.append(input())

counter = Counter(r)
for w, c in counter.most_common():
    if c > 1:
        ans += (c-1)*(p1+p2)
print(ans)