#include<bits/stdc++.h>
using namespace std;
const int N = 1e6;
const int inf = 2e9;
array <int,6> dp[N + 1];
int m[6][6] = {
{0,1,1,1,2,2},
{0,0,1,1,1,2},
{0,1,0,1,2,1},
{0,1,1,0,1,1},
{0,0,1,0,0,1},
{0,1,0,0,1,0}
};
int values[6] = {2,1,0,3,0,1};
bool v[N],v2[N];
int main(){
int n;
cin>>n;
for(int i = 0;i < n;i++){char ch;cin>>ch;v[i] = ch - '0';}
for(int i = 0;i < n;i++){char ch;cin>>ch;v2[i] = ch - '0';}
dp[0] = {0,inf,inf,inf,inf,inf};
///0 - empty 1 - on 2 - off
///3 - toggle 4 - on toggle 5 - off toggle
for(int i = 0;i < n;i++){
dp[i + 1] = {inf,inf,inf,inf,inf,inf};
for(int j = 0;j < 6;j++){
for(int k = 0;k < 6;k++){
int cost = m[j][k];
if((values[k] >= 2 && ((v[i]^v2[i]) == values[k] - 2)) || (values[k] <= 1 && values[k] == v2[i])){
dp[i + 1][k] = min(dp[i + 1][k], dp[i][j] + cost);
}
}
}
/*for(int j = 0;j < 6;j++){
cout<<dp[i + 1][j]<<' ';
}
cout<<'\n';*/
}
int ans = inf;
for(int j = 0;j < 6;j++)ans = min(ans, dp[n][j]);
cout<<ans;
return 0;
}
/**
12
010100101101
111000010010
on 0 6
toggle 3 11
**/
