#include<bits/stdc++.h>
using namespace std;
using ll = long long;
struct obj{
ll l, r, t, sp=-1,m=0; // all0 all1 other
};
int main(){
ios::sync_with_stdio(0);cin.tie(0);
ll n;
string a,b;
cin >> n >> a >> b;
vector<ll> dp0(n+1,1e18); // no
vector<ll> dp1(n+1,1e18); // 0
vector<ll> dp2(n+1,1e18); // 1
vector<ll> dp3(n+1,1e18); // rev
vector<ll> dp4(n+1,1e18); // 0+rev
vector<ll> dp5(n+1,1e18); // 1+rev
dp0[0] = 0;
dp1[0] = dp2[0] = dp3[0] = 1;
dp4[0] = dp5[0] = 2;
for(ll i = 0;i<n;i++){
if (a[i]==b[i]){
dp0[i+1] = min(min(min(min(min(dp0[i],dp1[i]),dp2[i]),dp3[i]),dp4[i]),dp5[i]);
}else{
dp3[i+1] = min(min(min(dp0[i],dp1[i]),dp2[i])+1,min(min(dp3[i],dp4[i]),dp5[i]));
}
if (b[i] == '1'){
dp2[i+1] = min(min(min(min(dp0[i],dp1[i]),dp3[i]),dp4[i])+1,min(dp2[i],dp5[i]));
dp4[i+1] = min(min(min(dp0[i],dp2[i])+2,min(min(dp1[i],dp3[i]),dp5[i])+1),dp4[i]);
}else{
dp1[i+1] = min(min(min(min(dp0[i],dp2[i]),dp3[i]),dp5[i])+1,min(dp1[i],dp4[i]));
dp5[i+1] = min(min(min(dp0[i],dp1[i])+2,min(min(dp2[i],dp3[i]),dp4[i])+1),dp5[i]);
}
}
ll ans = min(min(min(min(min(dp0[n],dp1[n]),dp2[n]),dp3[n]),dp4[n]),dp5[n]);
cout << ans << "\n";
}
