D

#include <bits/stdc++.h>

using namespace std;

#define ll     long long
#define _test   int _TEST; cin>>_TEST; while(_TEST--)

int main()
{
    _test
    {
        ll int n;
        string s, t;
        cin>>n>>s>>t;

        int seg = 0, i = 0;

        while(i<n)
        {
            if(s[i]!=t[i])
            {
                while(i<n && s[i]!=t[i])
                    i++;

                seg++;
            }
            else
                i++;
        }

        if(seg==1)
        {
            ll val = (n-1)*1ll*2;
            cout<<val<<"\n";
        }
        else if(seg==0)
            cout<<(n*1ll*(n+1)/2)<<"\n";
        else if(seg>2)
            cout<<0<<"\n";
        else
            cout<<6<<"\n";
    }
}