T=int(input())
for t in range(T):
    N,M=map(int,input().split())
    C0=[[0,0,0,1],[0,1,1,1]]
    C1=[[0,0,0,2,3,3,3,5,5],[0,1,2,2,2,3,4,5],[0,1,1,1,4,4,4,5]]
    XYC0=[(x,y,C0[x][y]) for x in range(2) for y in range(4)]
    XYC1=[(x,y,C1[x][y]) for x in range(3) for y in range(8)]
    ans_lst=[[None]*M for n in range(N)]
    def solve(N,M):
        if N%2==0 and M%4==0:
            retu=[[None]*M for n in range(N)]
            cur=1
            for n in range(0,N,2):
                for m in range(0,M,4):
                    for x,y,c in XYC0:
                        retu[n+x][m+y]=cur+c
                    cur+=2
        elif N>=2 and M%8==0:
            cur=1
            retu=[[None]*M for n in range(N)]
            if N%2:
                for m in range(0,M,8):
                    for x,y,c in XYC1:
                        retu[x][m+y]=cur+c
                    cur+=6
            for n in range(3 if N%2 else 0,N,8):
                for m in range(0,M,8):
                    for x,y,c in XYC1:
                        retu[n+x][m+y]=cur+c
                    cur+=6
        elif N%4==0 and M%2==0 or N%8==0 and M>=2:
            retu=solve(M,N)
            retu=[[retu[m][n] for m in range(M)] for n in range(N)]
        else:
            retu=None
        return retu
    ans_lst=solve(N,M)
    if ans_lst==None:
        print(-1)
    else:
        print(N*M//4)
        for n in range(N):
            print(*ans_lst[n])