#include <bits/stdc++.h>
using namespace std;
const int MAXN = 1e6 + 100;
int n;
string a,b;
int dp[MAXN][2][3];
int main() {
cin.tie(0);
ios::sync_with_stdio(0);
cin >> n;
cin >> a >> b;
memset(dp,0x66,sizeof(dp));
for(int inv=0;inv<2;inv++) {
for(int z=0;z<3;z++) {
dp[0][inv][z] = (inv == 1) + (z != 2);
}
}
for(int i=0;i<=n;i++) {
for(int inv=0;inv<2;inv++) {
for(int z=0;z<3;z++) {
//cout<<setw(10)<<dp[i][inv][z]<<" ";
if(b[i] == '0') {
dp[i+1][0][0] = min(dp[i+1][0][0],dp[i][inv][z] + (z != 0) );
dp[i+1][1][0] = min(dp[i+1][1][0],dp[i][inv][z] + (z != 0) + (inv != 1) );
}
if(b[i] == '1'){
dp[i+1][0][1] = min(dp[i+1][0][1],dp[i][inv][z] + (z != 1) );
dp[i+1][1][1] = min(dp[i+1][1][1],dp[i][inv][z] + (z != 1) + (inv != 1) );
}
if(b[i] == a[i]) dp[i+1][0][2] = min(dp[i+1][0][2],dp[i][inv][z] );
else dp[i+1][1][2] = min(dp[i+1][1][2],dp[i][inv][z] + (inv != 1) );
}
}//cout<<endl;
}
int rs = 1e9;
for(int inv=0;inv<2;inv++) {
for(int z=0;z<3;z++) {
rs = min(rs,dp[n][inv][z]);
}
}
cout<<rs<<'\n';
return 0;
}
