yes=[0]*10
no=[0]*10
Y=0
N=0
n=int(input())

for i in range(n):
    a=list(map(str,input().split()))
    if a[-1]=="NO":
        N+=1
        for j in a[:-1]:
            no[int(j)]+=1
    else:
        Y+=1
        for j in a[:-1]:
            yes[int(j)]+=1

if Y==0:
    print(no.index(0))
elif N==0:
    print(yes.index(2))
else:
    for i in range(10):
        if yes[i]==2 and no[i]==0:
            print(i)
            exit()