#include<bits/stdc++.h>
using namespace std;
int read(){
    int x=0;char ch=getchar();
    while (!isdigit(ch)) ch=getchar();
    while (isdigit(ch)) x=x*10+ch-48,ch=getchar();
    return x;
}
void solve(){
    int ql=read(),qr=read();
    if (ql==qr) return puts("-1"),void();
    if (qr-ql&1){
        for (int i=ql;i<=qr;i++)
            printf("%d ",i+(i-ql&1?-1:1));
        return puts(""),void();
    }
    if (~ql&1) return puts("-1"),void();
    printf("%d %d %d ",ql+1,ql+2,ql);
    for (int i=ql+3;i<=qr;i++)
        printf("%d ",i+(i-ql&1?1:-1));
    puts("");
}
int main(){int T=read();while (T--) solve();return 0;}