x = list(input())
y = int(input())
while len(x) >= 10:
    tmp = int("".join(x[:3]))
    if tmp < y:
        tmp = int("".join(x[:4]))
        tmp -= y
        x[0] = str(tmp // 1000)
        tmp = tmp % 1000
        x[1] = str(tmp // 100)
        tmp = tmp % 100
        x[2] = str(tmp // 10)
        tmp = tmp % 10
        x[3] = str(tmp)
    else:
        tmp -= y
        x[0] = str(tmp // 100)
        tmp = tmp % 100
        x[1] = str(tmp // 10)
        tmp = tmp % 10
        x[2] = str(tmp)
    while x[0] == "0":
        x = x[1:]
print(int("".join(x)) % y)