#include<bits/stdc++.h>
using namespace std;
#define int long long
#define PII pair<int,int>
#define x first
#define y second
void solve() {
	int n;
	cin>>n;
	string s,t;
	cin>>s>>t;
	if(s==t){
		cout<<(n+1)*n/2<<"\n";
	}else{
		s=" "+s;
		t=" "+t;
		vector<PII> a;
		for(int i=1;i<=n;i++){
			int j=i;
			if(s[i]!=t[i]){
				while(j<=n&&s[j]!=t[j]){
					j++;
				}
				a.push_back({i,j-1});
				i=j-1;
			}
		}
		if(a.size()>2){
			cout<<"0\n";
		}else if(a.size()==1){
			int ans=0;
			if(n==1){
				cout<<"0\n";
			}else{
				int l=a[0].x,r=a[0].y;
				ans=(r-l)*2;
				ans+=(n-(r-l+1))*2;
				cout<<ans<<"\n";
			}
		}else{
			int ans=6;
			cout<<ans<<"\n";
		}
	}
}
signed main() {
	ios::sync_with_stdio(0);
	cin.tie(0),cout.tie(0);
	int T=1;
	cin>>T;
	while(T--) {
		solve();
	}
	return 0;
}