#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
#define rep(a,b) for(int a = 0; a < (b); ++a)
#define all(t) t.begin(), t.end()
#define pb push_back
const int N = 1e6+54321, INF = 2e9+54321;
const ll INF_L = (ll)2e18+54321;
int n,wyn;
string A,B;
int dp[N], dpS[N], dp0[N], dp1[N], dp0S[N], dp1S[N];
void solve()
{
cin >> n >> A >> B;
if(A[0] == B[0])
{
dp[0] = 0, dpS[0] = 2;
}
else
{
dp[0] = 1, dpS[0] = 1;
}
if(B[0] == '0')
{
dp0[0] = 1, dp1[0] = INF;
}
else
{
dp1[0] = 1, dp0[0] = INF;
}
if(B[0] == '0')
{
dp0S[0] = INF, dp1S[0] = 2;
}
else
{
dp1S[0] = INF, dp0S[0] = 2;
}
for(int i = 1; i < n; ++i)
{
int co = min({dp[i-1],dpS[i-1],dp0[i-1],dp1[i-1],dp0S[i-1],dp1S[i-1]});
if(A[i] == B[i]) dp[i] = co;
else dp[i] = co+1;
if(A[i] != B[i])
{
dpS[i] = min({dpS[i-1],dp0S[i-1],dp1S[i-1],co+1});
}
else if(B[i] == '0') dpS[i] = min({co+2,dp1S[i-1]});
else dpS[i] = min({co+2,dp0S[i-1]});
if(B[i] == '0')
{
dp0[i] = min({dp0[i-1],dp0S[i-1],co+1});
}
else dp0[i] = INF;
if(B[i] == '1')
{
dp1[i] = min({dp1[i-1],dp1S[i-1],co+1});
}
else dp1[i] = INF;
if(B[i] == '1')
{
dp0S[i] = min({dp0S[i-1],co+2,dp0[i-1]+1});
}
else dp0S[i] = INF;
if(B[i] == '0')
{
dp1S[i] = min({dp1S[i-1],co+2,dp1[i-1]+1});
}
else dp1S[i] = INF;
}
int res = min({dp[n-1],dpS[n-1],dp0[n-1],dp1[n-1],dp0S[n-1],dp1S[n-1]});
cout << res << '\n';
}
int main()
{
ios_base::sync_with_stdio(0);
cin.tie(0);
int T = 1;
//cin >> T;
while(T--) solve();
return 0;
}
