#include<bits/stdc++.h>
#define de fprintf(stderr,"on-%d\n",__LINE__)
//#define int long long
#define fr(i,a,b) for(int i(a),end##i(b);i<=end##i;i++)
#define fd(i,a,b) for(int i(a),end##i(b);i>=end##i;i--)
#define fi first
#define se second
#define pii pair<int,int>
#define mk make_pair
using namespace std;
const int maxn=2500;
int n;
int a[maxn],b[maxn],p[maxn],q[maxn];
pii ans[maxn*maxn];
int A[maxn],tp;
int top;
void solve(){
	scanf("%d",&n);
	fr(i,1,n){
		scanf("%d",&a[i]);
		p[a[i]]=i;
	}
	fr(i,1,n){
		scanf("%d",&b[i]);
		q[b[i]]=i;
	}
	top=0;
	a[n+1]=n+1;
	fr(i,1,n){
		if(p[i]<q[i]||a[q[i]]<i){
			printf("-1\n");
			return ;
		}
		int Min=n+1;
		//fd(j,p[i]-1,q[i])if(a[j]>i&&a[j]<a[pos])pos=j;
		tp=0;
		fr(j,q[i],p[i]-1)if(a[j]>i){
			if(a[j]<Min){
				Min=a[j];
				A[++tp]=j;
			}
		}
		A[tp+1]=p[i];
		fd(j,tp,1){
			swap(a[A[j]],a[A[j+1]]);
			swap(p[a[A[j]]],p[a[A[j+1]]]);
			ans[++top]=mk(A[j],A[j+1]);
		}
		//fr(j,1,n)printf("%d ",a[j]);printf("\n");
	}
	printf("%d\n",top);
	fr(i,1,top)printf("%d %d\n",ans[i].fi,ans[i].se);
}
signed main(){
#ifdef pig
	freopen("pig.in","r",stdin);
	freopen("pig.out","w",stdout);
#endif
	int t;cin>>t;
	while(t--){
		solve();
	}
	return 0;
}