let t = stdin.ReadLine() |> int

let f n m =
    let cnts = Array.zeroCreate<int> n
    for i = 0 to m - 1 do
        let [| u; v |] =
            stdin.ReadLine().Split()
            |> Array.map int
        cnts.[u-1] <- cnts.[u-1] + 1
        cnts.[v-1] <- cnts.[v-1] + 1
    cnts

for i = 0 to t - 1 do
    let [| n; m |] =
        stdin.ReadLine().Split()
        |> Array.map int
    let cnts = f n m

    Array.sortInPlace cnts
    let mutable flg = false
    for i = 1 to cnts.Length - 1 do
        if cnts.[i] = cnts.[i-1] then
            flg <- true

    if flg then
        "Yes"
    else
        "No"
    |> printfn "%s"