#include<bits/stdc++.h>
#define ff first
#define ss second
#define pb push_back
using namespace std;
typedef long long ll;
typedef pair<int,int> pii;

const int mod=998244353;
inline int add(int x,int y){int ret=x+y;if(ret>=mod)ret-=mod;return ret;}
inline int sub(int x,int y){int ret=x-y;if(ret<0)ret+=mod;return ret;}
inline int mul(int x,int y){return ((ll)x*y)%mod;}
inline int step(int base,int pw){int ret=1;while(pw){if(pw&1)ret=mul(ret,base);base=mul(base,base);pw>>=1;}return ret;}
inline int invv(int x){return step(x,mod-2);}

const int maxn=3e5+10;

ll A,B,a[maxn],dp[maxn],inf=1e18;
int fdl[maxn],n;

int main(){

    ///freopen("test.txt","r",stdin);

    int t;
    scanf("%d",&t);
    while(t--){

        scanf("%d %lld %lld",&n,&A,&B);
        n=2*n;
        for(int i=1;i<=n;i++){
            scanf("%lld",&a[i]);
        }
        sort(a+1,a+n+1);

        dp[1]=-inf;
        fdl[1]=1;
        int lp=1;
        for(int i=2;i<=n;i++){

            while(a[i]-a[lp]>A)lp++;
            fdl[i]=i;
            if(a[i]-a[i-1]<=B){
                fdl[i]=i-2;
                fdl[i]=min(fdl[i],fdl[i-2]);
            }

            int pom=max(fdl[i-1],lp);
            if((i-pom)%2==0)pom++;

            dp[i]=-inf;
            dp[i]=max(dp[pom-1]+(i-pom)/2,dp[i]);
            if(a[i]-a[i-1]<=B)dp[i]=max(dp[i],dp[i-2]+1);
        }

        if(dp[n]<0)printf("-1\n");
        else printf("%lld\n",dp[n]);

    }

    return 0;
}