#include<bits/stdc++.h>
using namespace std;

typedef long long LL;
typedef pair<int,int> P;
const LL mod=998244353;
const int INF=0x3f3f3f3f;
const int N=1e5+10;
string s,t;
int n;

void solve()
{
    cin>>n;
    cin>>s>>t;
    
    s=" "+s;
    t=" "+t;
    
    int cnt=0;
    int l=0,r=0;
    
    for(int i=1;i<=n;i++)
        if(s[i]!=t[i])
        {
            l=r=i;
            
            while(s[r]!=t[r]&&r<=n) r++;
            r--;
            
            cnt++;
            
            i=r;
        }
    
    if(cnt==0) cout<<n*(n+1)/2<<endl;
    else if(cnt==1) cout<<(r-l)*2+(l-1)*2+(n-r)*2<<endl;
    else if(cnt==2) cout<<6<<endl;
    else cout<<0<<endl;
}

int main()
{
    ios::sync_with_stdio(0);
    cin.tie(0); cout.tie(0);
    
    int tt; cin>>tt;
    
    while(tt--) solve();
    
    return 0;
}