var re = /(?!^nin)(nin$)/gm;
var str = 'suyunin\nabcninshs\nning\ngnin\nning\nkinindan*\nsininteki\nnin\nninkisi';
var subst = 'NG';
var result = str.replace(re, subst);
print(result)
dmFyIHJlID0gLyg/IV5uaW4pKG5pbiQpL2dtOyAKdmFyIHN0ciA9ICdzdXl1bmluXG5hYmNuaW5zaHNcbm5pbmdcbmduaW5cbm5pbmdcbmtpbmluZGFuKlxuc2luaW50ZWtpXG5uaW5cbm5pbmtpc2knOwp2YXIgc3Vic3QgPSAnTkcnOyAKIAp2YXIgcmVzdWx0ID0gc3RyLnJlcGxhY2UocmUsIHN1YnN0KTsKcHJpbnQocmVzdWx0KQ==