import re
p = re.compile(r'(?<=-)\d+(?=/|$)')
test_str = "http://52portal/flood-2011-year-39090/gallery?p=3\nhttp://52portal/flood-2011-year-39090"
print(re.findall(p, test_str))
aW1wb3J0IHJlCnAgPSByZS5jb21waWxlKHInKD88PS0pXGQrKD89L3wkKScpCnRlc3Rfc3RyID0gImh0dHA6Ly81MnBvcnRhbC9mbG9vZC0yMDExLXllYXItMzkwOTAvZ2FsbGVyeT9wPTNcbmh0dHA6Ly81MnBvcnRhbC9mbG9vZC0yMDExLXllYXItMzkwOTAiCnByaW50KHJlLmZpbmRhbGwocCwgdGVzdF9zdHIpKQ==