s=["o-o","-oo","oo-","-o--","--o-","o-o-o","ooo","o---o"]
for _ in range(int(input())):
    a,b=input().split();ans="X"
    c=0;d=1
    while d<len(s)-1:
    	if s[d]=="-" and (s[d-1]=="o" or s[d-1]=="-"):
    		c+=1
    	elif s[d]=="o":
    		if c&1 and s[d+1]=="o":
    			ans="O"
    	if s[d]!="-":
    		c=0
    	d+=1
    for i in range(len(b)):
        for j in s:
            if b[i:i+len(j)]==j:
                ans="O"
    print(ans)