def happyLadyBugs(b):
    for i in b:
        if i != "_" and b.count(i) == 1:
            return "NO"
            break
    
    if (b.count("_") > 0):
        return "YES"
    
    z = list(zip(b, b[1:], b[2:]))
    
    return "YES" if all(map(lambda t: t[1]==t[0] or t[1]==t[2], z)) else "NO"

g = int(input())
for i in range(g):
    n = int(input())
    b = input()
    
    result = happyLadyBugs(b)
    
    print(result)