N=int(input())
S=input().strip()
T=input().strip()

U=S[::-1]

x=0
y=0

for i in range(N):
    if S[i]!=T[i]:
        x+=1

    if U[i]!=T[i]:
        y+=1

if x%2==1:
    x=1<<64
if y%2==0:
    y=1<<64

print(min(x,y))