#include <stdio.h>
#include <string.h>
#define N 1000000
#define INF 0x3f3f3f3f
int min(int a, int b) { return a < b ? a : b; }
int main() {
static char aa[N + 1], bb[N + 1];
static int dp[5], dq[5];
int n, i, s, x, ans;
scanf("%d%s%s", &n, aa, bb);
for (i = 0; i < n; i++)
aa[i] -= '0', bb[i] -= '0';
memset(dp, 0x3f, sizeof dp), dp[4] = 0;
for (i = 0; i < n; i++) {
int a = i == 0 ? 0 : aa[i - 1], b = i == 0 ? 0 : bb[i - 1];
memset(dq, 0x3f, sizeof dq);
if ((x = dp[0]) != INF) {
dq[0] = min(dq[0], x + (b == 0 && bb[i] != 0 ? 1 : 0));
dq[3] = min(dq[3], x + (b == 0 && bb[i] != 1 ? 1 : 0) + 1);
dq[4] = min(dq[4], x + (b == 0 && bb[i] != aa[i] ? 1 : 0));
}
if ((x = dp[1]) != INF) {
dq[1] = min(dq[1], x + (b == 0 && bb[i] != 0 ? 1 : 0));
dq[2] = min(dq[2], x + (b == 0 && bb[i] != 1 ? 1 : 0));
dq[4] = min(dq[4], x + (b == 0 && bb[i] != aa[i] ? 1 : 0));
}
if ((x = dp[2]) != INF) {
dq[1] = min(dq[1], x + (b == 1 && bb[i] != 0 ? 1 : 0) + 1);
dq[2] = min(dq[2], x + (b == 1 && bb[i] != 1 ? 1 : 0));
dq[4] = min(dq[4], x + (b == 1 && bb[i] != aa[i] ? 1 : 0));
}
if ((x = dp[3]) != INF) {
dq[0] = min(dq[0], x + (b == 1 && bb[i] != 0 ? 1 : 0));
dq[3] = min(dq[3], x + (b == 1 && bb[i] != 1 ? 1 : 0));
dq[4] = min(dq[4], x + (b == 1 && bb[i] != aa[i] ? 1 : 0));
}
if ((x = dp[4]) != INF) {
dq[0] = min(dq[0], x + (b == a && bb[i] != 0 ? 1 : 0) + 1);
dq[2] = min(dq[2], x + (b == a && bb[i] != 1 ? 1 : 0) + 1);
dq[4] = min(dq[4], x + (b == a && bb[i] != aa[i] ? 1 : 0));
}
memcpy(dp, dq, sizeof dq);
}
ans = INF;
for (s = 0; s < 5; s++)
ans = min(ans, dp[s]);
printf("%d\n", ans);
return 0;
}
