toI(s=readline()) = parse(Int,s)
toVI(s=readline()) = parse.(Int,split(s))
rep(f,n) = [f() for _ in 1:n]
@enum YN Yes=1 No=0

function main()
    t = toI()
    for _ in 1:t
        n = toI()
        xys = rep(split∘readline,n)
        solve(n,xys) |> YN |> println
    end
end

function solve(n,xys)
    sort!(xys)
    mx = 0
    for (x,y) in xys
        if x == "a"
            if 'a' ∈ y
                return true
            else # y == "b...b" 
                mx = max(mx,length(y))
            end
        elseif 'a' ∉ x && length(x) ≤ mx # x == "b...b"
            if 'a' ∈ y
                return true
            else # y == "b...b"
                return true
            end
        end
    end
    return false
end

@static if endswith(@__FILE__, PROGRAM_FILE)
    main()
end