到底哪里出问题啦？

import math
s,v=map(int,input().split())
t=s/v
if t<50:
    b=str(math.floor(50-t)).rjust(2,'0')
    print('07:{}'.format(b))
else:
    T=t-50
    if T<=420:
        m=str(math.floor(60-T%60)).rjust(2,'0')
        while m=='60':
            m='00'
        h=str(7-int(T/60)).rjust(2,'0')
        print("{}:{}".format(h,m))
    elif T>420 and T<=1860:
        m=str(math.floor(60-T%60)).rjust(2,'0')
        while m=='60':
            m='00'
        h=str(24-int(T/60)+7).rjust(2,'0')
        print("{}:{}".format(h,m))
    else:
        print('不符合题意！')