hour_minute = str(input()).split(':')
hours = int(hour_minute[0])
minutes = int(hour_minute[1])
minutes_modifier = int(input())
hours_duration = int(input())
hours_in_minutes = hours * hours_duration
total_minutes = (hours_in_minutes + minutes) / (minutes_modifier * 1.)
terra_minutes = total_minutes % 60
terra_hours = (total_minutes - terra_minutes) / 60
terra_hours = terra_hours % 24
print(str(int(terra_hours)) + ':' + str(int(terra_minutes)))