#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
using namespace std;
using namespace __gnu_pbds;
#define ord_set tree < int , null_type , less , rb_tree_tag , tree_order_statistics_node_update>
#define ll unsigned long long
#define rep(i,a,b) for (int i = a; i < b; i++)
#define rrep(i,a,b) for (int i = a; i >= b; i--)
void N() {cout<<"NO\n";}
void Y() {cout<<"YES\n";}
void isTrue(bool ope) {
if (ope) Y();else N();
}
int MD = 1e9+7;
ll MX_VL = 1e18;
int MX_ll = 2e9;
vector<int> T;
vector<int> H;
vector<int> pref;
vector<int> pref2;
vector<int> pnt;
vector<int> cnc2;
int m;
int n;
void initialize(std::vector<int> Tp, std::vector<int> Hp) {
T = Tp;
H = Hp;
m = Hp.size();
n = Tp.size();
pref.resize(m, 0);
pref2.resize(m, 0);
pref2[0] = H[0] >= 2;
pref[0] = Tp.back() <= Hp[0];
rep(i, 0, m) {
if (H[i] == 0) pnt.push_back(i);
if (H[i] >= 2) {
cnc2.push_back(i);
pref2[i] = pref2[i - 1] + 1;
} else pref2[i] = pref2[i - 1];
}
rep(i, 1, m) {
pref[i] = (Tp.back() <= Hp[i]) + pref[i - 1];
}
}
bool can_reach(int L, int R, int S, int D) {
auto tt = lower_bound(cnc2.begin(),cnc2.end(),S);
if (tt == cnc2.end() || *tt > D) return true;
if (pnt.empty()) return false;
auto i1 = lower_bound(cnc2.begin(),cnc2.end(),D);
int l = *prev(i1,1);
int r = i1 != cnc2.end() ? *i1 : m;
int l2 = tt == cnc2.begin() ? -1 : *prev(tt,1);
int r2 = *tt;
auto j = *lower_bound(pnt.begin(),pnt.end(),l2);
auto i = *lower_bound(pnt.begin(),pnt.end(),l);
return j <= r2 && i <= r && pref[i]==pref[j];
}
void solve() {
int n;
cin>>n;
string a,b;
cin>>a>>b;
vector<int> c1(n);
vector<int> c2(n);
int c1o = b[0]!=a[0];
int c2o = b[0]!=a[0];
c1[0] = c1o;
ll sm1 = 0;
rep(i,1,n) {
c1o += b[i]!=a[0];
c1[i] = min(i+2-c1o,c1o);
sm1 += c1[i];
}
rep(i,1,n) {
c2o += a[i]!=b[0];
c2[i] = min(i+2-c2o,c2o);
}
ll ans = sm1+c2[0];
rep(i,1,n) {
if (c2[i]!=c2[i-1]) sm1+=n-1;
ans+=sm1;
}
cout << ans << endl;
}
