lines = [x.strip() for x in open("input.txt")]

timestamp = int(lines[0])
busses = (int(x) for x in lines[1].split(',') if x != 'x')
next_departures = ((x, timestamp // x * x + x) for x in busses)
next_bus = min(next_departures, key=lambda x: x[1])
print(next_bus[0] * (next_bus[1]-timestamp))