〜さえ〜ば

Meaning

Expresses that if just one single condition is met, that alone is sufficient for what follows to hold. Out of many possible elements, it singles out just that one point and emphasizes that it alone is necessary and sufficient. Used with a nuance of "as long as at least that condition exists."

Examples

薬さえ飲めば、熱はすぐに下がるはずだ If you just take the medicine, the fever should come down quickly.
お金さえあれば幸せだとは限らない Having money does not necessarily mean happiness.
ボタンを押しさえすれば機械は動く You only need to press the button and the machine will work.
君さえそばにいてくれれば、ほかには何もいらない As long as you are by my side, I do not need anything else.