#!/usr/local/bin/python3

sta = 'yamada'
b = [('suzuki', 'satou'), ('yamada', 'tanaka'), ('tanaka', 'satou'), ('watanabe', 'suzuki')]

ans = []
cur = sta
ans.append(cur)
bb = copy(b)

while b:
    for i, pair in enumerate(b):
        if cur in pair: break
    del b[i]
    cur = pair[1] if pair[0] == cur else pair[0]
    ans.append(cur)

print(ans)