import re
pattern = r"^.*?\b(\d{3})(?!\d)"
s = ("\"Depart: NYC (etd 9/30), NJ (etd 10/4)\n"
"Arrive LAX\n"
"Rate: USD500, 700P\"\n")
m = re.search(pattern, s, re.DOTALL)
if m:
print (m.group(1))
aW1wb3J0IHJlCiAKcGF0dGVybiA9IHIiXi4qP1xiKFxkezN9KSg/IVxkKSIKcyA9ICgiXCJEZXBhcnQ6IE5ZQyAoZXRkIDkvMzApLCBOSiAoZXRkIDEwLzQpXG4iCgkiQXJyaXZlIExBWFxuIgoJIlJhdGU6IFVTRDUwMCwgNzAwUFwiXG4iKQogCm0gPSByZS5zZWFyY2gocGF0dGVybiwgcywgcmUuRE9UQUxMKQppZiBtOgoJcHJpbnQgKG0uZ3JvdXAoMSkp