s,v = map(int,input().split())
T = 10

if(s % v == 0):
    t = s / v
    t += 10
else:
    t = s / v
    t += 9

H = 7
M = 59

while(t > 0):
    if(M != 0):
        M -= 1
    else:
        if(H == 0):
            H = 23
            M = 59
        else:
            H -= 1
            M = 59
    t -= 1

h1 =  int(H / 10)
h2 = H - (10*h1)
m1 = int((M / 10))
m2 = M - (10*m1)

print("{0}{1}:{2}{3}".format(h1,h2,m1,m2))