N = int(input())
inp = []
for i in range(N):
    inp.append(input().split())
    
pos = list('0123456789')

for t in inp:
    isIn = t.pop(-1)
    if isIn == "NO":
        for n in t:
            if n in pos:
                pos.remove(n)
            else:
                continue
    else:
        common = list(set(t) & set(pos))
        if common:
            pos = common
        else:
            pos.extend(t)
        pos = list(sorted(set(pos)))

ans = pos[0]
print(ans)