2週4日目 君さえいれば
Value・ability・condition
接続：N＋でさえ
even in case of emphasis
注意 / Note：〜さえ is attached to a noun indicating a person or situation, to give an example that SHOULD be different. Saying 専門家でさえ迷った means that experts are still confused, let alone ordinary people.
比較 / Compare：Same song: 〜さえ／〜さえ〜ば. These models are often mistakenly chosen for each other — carefully read the 接続 and nuances above and then decide.
よく出る形 / Common form：名詞＋でさえ。Or go with 専門家・大人・先生・本人. The latter part often carries a tone of surprise or complaint.
専門家でさえ判断に迷った。
Even experts are confused.
この問題は先生でさえ難しい。
Even teachers find this lesson difficult.
地元の人でさえ知らない小さな滝がある。
There is a small waterfall that even local people do not know about.