/*
+----------------------------------------------------------------+
| In the name of Allah, the most Gracious and the most Merciful. |
+----------------------------------------------------------------+
Our hearts quake with fear of you
Our hearts wake with love for you
And to Islam we must be true
In everything we think and do.
--------------------------------
When your heart is breaking
And your pain makes you fall
Remember just remember
Allah Sees it all.
*/
# include <bits/stdc++.h>
# define FILE
using namespace std;
const int N = 1e6 + 100;
const int inf = 1e9;
string A,B;
int n;
vector < vector < int > > dp[N];
char op(int x, char c){
if( x == 0 ) return c;
if( x == 1 ) return '0';
if( x == 2 ) return '1';
if( c == '1' ) return '0';
return '1';
}
int main(){
# ifdef FILEs
freopen( "input.txt", "r", stdin );
freopen( "output.txt", "w", stdout );
# endif
ios_base::sync_with_stdio(false);
cin >> n >> A >> B;
A = '0' + A;
B = '0' + B;
dp[0].push_back({0,0,0,0});
for( int i = 1; i <= n; i ++ ){
for( int a = 0; a < 4; a ++ ){
for( int b = 0; b < 4; b ++ ){
for( int c = 0; c < 4; c ++ ){
if( op(c,op(b,op(a,A[i]))) != B[i] )
continue;
int mn = inf;
for( auto vc: dp[i-1] ){
int cost = vc[3] + (vc[0]!=a && a) +
(vc[1]!=b && b) +
(vc[2]!=c && c);
mn = min(mn, cost);
}
if( mn < inf )
dp[i].push_back({a,b,c,mn});
}
}
}
}
int ans = inf;
for( auto vc: dp[n] )ans = min( ans, vc[3] );
cout << ans;
}
