#include<bits/stdc++.h>
#define ios ios::sync_with_stdio(0),cin.tie(0),cout.tie(0)
using namespace std;using ll = long long;using PLL = pair<ll,ll>;
const ll MAX = 1e18;const ll MIN = -1e18;const ll INF=0x3f3f3f3f;
const ll Q = 2e5+9;const ll MOD = 1e9 + 7;
string a,b;
void solve(){
   ll n;cin>>n;
   cin>>a>>b;
   if(a==b){
    cout<<n+n*(n-1)/2;
    return;
   }
   ll l=0,r=0;
   ll cnt=0;
   for (ll i = 0; i < n; i++)
   {
    if(a[i]!=b[i]) cnt++;
    else {
        if(cnt!=0){
            if(l==0) l=cnt;
            else if(r==0) r=cnt;
            else {
                cout<<"0\n";
                return;
            }
        }
        cnt=0;
    }
   }
   if(cnt!=0){
            if(l==0) l=cnt;
            else if(r==0) r=cnt;
            else {
                cout<<"0\n";
                return;
            }
        }

   if(l!=0 and r!=0){
    cout<<6<<"\n";
   }else {
    cout<<(n-1)*2<<"\n";
   }
}
int main(){
    ios;ll _=1;cin>>_;
    while (_--)solve();
    return 0;
}