#include <bits/stdc++.h>
#define N 1000005
#define INF 1000000000
using namespace std;
void chmin(int& a, int v) {
a = min(a,v);
}
/*
0 - none
1 - flip
2 - ons
3 - offs
4 - flip, ons
5 - flip, offs
6 - ons, flip
7 - offs, flip
*/
int n, dp[N][8];
string A, B;
int main() {
cin.tie(0)->sync_with_stdio(0);
cin >> n >> A >> B;
for(auto&i: dp) for(auto&j: i) j = INF;
dp[0][0] = 0;
for(int i = 0; i < n; i ++) {
if(A[i] == B[i]) {
chmin(dp[i+1][0],min({dp[i][0],dp[i][1],dp[i][2],dp[i][3],dp[i][4],dp[i][5],dp[i][6],dp[i][7]}));
} else {
chmin(dp[i+1][1],min({dp[i][0]+1,dp[i][1],dp[i][4],dp[i][5],dp[i][6],dp[i][7]}));
}
if(B[i] == '1') {
chmin(dp[i+1][2],min({dp[i][0]+1,dp[i][2],dp[i][4],dp[i][6]}));
chmin(dp[i+1][6],min({dp[i][6],dp[i][1]+1}));
chmin(dp[i+1][5],min({dp[i][5],dp[i][3]+1}));
} else {
chmin(dp[i+1][3],min({dp[i][0]+1,dp[i][3],dp[i][5],dp[i][7]}));
chmin(dp[i+1][4],min({dp[i][4],dp[i][2]+1}));
chmin(dp[i+1][7],min({dp[i][7],dp[i][1]+1}));
}
}
int ans = INF;
for(int i = 0; i < 8; i ++) {
ans = min(ans, dp[n][i]);
}
cout << ans;
}
