#include <bits/stdc++.h>
using namespace std;
#define int int64_t
int32_t main() {
int N; cin >> N; string A, B; cin >> A >> B;
int dp[N][6];
if(A[0] == B[0]) dp[0][0] = 0;
else dp[0][0] = 1e15;
if(B[0] == '0') dp[0][1] = 1;
else dp[0][1] = 1e15;
if(B[0] == '1') dp[0][2] = 1;
else dp[0][2] = 1e15;
if(A[0] != B[0]) dp[0][3] = 1;
else dp[0][3] = 1e15;
dp[0][4] = 2; dp[0][5] = 2;
for(int i = 1; i < N; i++) {
int minprev = 1e15, minFlip, min0, min1;
for(int j = 0; j < 6; j++) minprev = min(minprev, dp[i - 1][j]);
min0 = min(dp[i - 1][1], dp[i - 1][4]);
min1 = min(dp[i - 1][2], dp[i - 1][5]);
minFlip = min(dp[i - 1][3], min(dp[i - 1][4], dp[i - 1][5]));
if(A[i] == B[i]) dp[i][0] = minprev;
else dp[i][0] = 1e15;
if(B[i] == '0') dp[i][1] = min(minprev + 1, min0);
else dp[i][1] = 1e15;
if(B[i] == '1') dp[i][2] = min(minprev + 1, min1);
else dp[i][2] = 1e15;
if(A[i] != B[i]) dp[i][3] = min(minprev + 1, minFlip);
else dp[i][3] = 1e15;
dp[i][4] = min(minprev + 2, min0 + 1);
dp[i][4] = min(dp[i][4], minFlip + 1);
if(B[i] == B[i - 1]) {
dp[i][4] = min(dp[i][4], dp[i - 1][4]);
}
dp[i][5] = min(minprev + 2, min1 + 1);
dp[i][5] = min(dp[i][5], minFlip + 1);
if(B[i] == B[i - 1]) {
dp[i][5] = min(dp[i][5], dp[i - 1][5]);
}
}
int ans = 1e15;
for(int i = 0; i < 6; i++) ans = min(ans, dp[N - 1][i]);
cout << ans;
}
