n = int(input())
s = input()
t = input()
ans = 0
for i in range(n):
  if s[i] != t[i]:
    ans += 1
ans2 = 0
s = s[::-1]
for i in range(n):
  if s[i] != t[i]:
    ans2 += 1
 
print(min(ans,ans2))