def main():
    n, m = [int(i) for i in input().split()]
    uv = [[int(i) for i in input().split()] for i in range(m)]

    if m==n*(n-1)/2:
        print(3)
        out = []
        u, v = uv[0]
        for a, b in uv:
            if (a, b) == (u, v):
                out.append(1)
            elif a==u or b==u:
                out.append(2)
            else:
                out.append(3)
        return " ".join([str(i) for i in out])

    # Trouver un sommet de degré != n-1
    degs = [0 for _ in range(n)]

    for u, v in uv:
        degs[u-1] += 1
        degs[v-1] += 1

    j=-1
    for i in range(n):
        if degs[i] < n-1:
            j = i+1
            break
    if j==-1:
        return

    

    print(2)
    out = []
    for u, v in uv:
        if u==j or v==j:
            out.append(2)
        else:
            out.append(1)
    
    return " ".join([str(i) for i in out])

for _ in range(int(input())):
    print(main())