i = open("DATA5.txt")
lines = i.readlines()
i.close()

output = ""
mode = 0;
class node:
    i = 0;
for line in map(lambda x: x.strip(),lines):
    if mode == 0:
        firstnode = ""
        nodelist = [0]*101
        mode = 1
        length = int(line)
        N = length
        continue
    if mode == 1:
        elements = line.split(" ")
        if firstnode == "": firstnode = int(elements[0])
        nodelist[int(elements[0])] = node()
        nodelist[int(elements[0])].i = int(elements[1])
        N -= 1
        if N == 0:
            mode = 0
            #print nodelist
            count = 1
            cnode = firstnode
            while(nodelist[cnode].i != firstnode):
                cnode = nodelist[cnode].i
                count += 1
            output += str(count)+"\n"

print output
output = output.strip()
o = open("OUT5.txt","w")
o.write(output)
o.close()