#include<bits/stdc++.h>
using namespace std;
#define int long long 
const int NN=998244353;
int a[100100],b[100100],f[100100];
void solve(){
    int ans=0,n;
    cin>>n;
    for (int i=1;i<=n;i++)
    cin>>a[i]>>b[i],f[i]=0;
    int l=0,r=0,pl=0,pr=0;
    f[0]=1;
    for (int i=1;i<=n;i++){
        if(a[i]!=-1&&a[i]+b[i]!=i)return cout<<0<<"\n",void();
        if(i<=20)l=0,r=i;
        else if(i==n)l=max((i-2)/2-1,0ll),r=min(i-l+1,i);
        else l=(i-2)/2,r=i-l;
        // cout<<i<<"!!!"<<l<<" "<<r<<"\n";
        // l=0,r=i;
        if(a[i]==-1){
            for (int j=r;j>=l;j--)
            f[j]=(f[j]+f[j-1])%NN;
            for (int j=pl;j<l;j++)f[j]=0;
        }else{
            int tmp1=(a[i]==0)?0:f[a[i]-1];
            int tmp2=f[a[i]];
            int tmp3=(b[i]==0)?0:f[b[i]-1];
            int tmp4=f[b[i]];
            for (int j=pl;j<=pr;j++)
            f[j]=0;
            f[a[i]]=(tmp1+tmp2)%NN;
            f[b[i]]=(tmp3+tmp4)%NN;
        }
        if(i!=n)
        for (int j=l;j<=r;j++)
        if(j>=11||i-j>=11){
            if(abs(j-(i-j))>=2)f[j]=0;
        }
        // for (int j=l;j<=r;j++)
        // cout<<i<<" "<<j<<" "<<f[j]<<"\n";
        pl=l,pr=r;
    }
    for (int i=pl;i<=pr;i++)
    if(i>=11||n-i>=11){
        if(abs(i-(n-i))>=2)ans=(ans+f[i])%NN;
    }
    cout<<ans<<"\n";
}
signed main(){
    ios::sync_with_stdio(0);
    cin.tie(0);cout.tie(0);
    int T;cin>>T;
    while(T--)solve();
}