print((function (h0, m0, d, d0)
	local t=(h0+d-d0)*60+m0
	local h,m=math.floor(t/60)%24,t%60
	if m>59 then h,m=h+1,0 end
	if h==24 then h=0 end
	return string.format("%02.0f:%02.0f",h,m)
end)(io.stdin:read("*n"), io.stdin:read("*n"), tonumber(io.stdin:read("*l"):sub(5)), 9))