T,A,B = map(int,input().split())

def gcd(a,b):
    while True:
        r = a % b
        a = b
        b = r
        if r == 0:
            return a
C = A * B // gcd(A,B)

T -= 1
print(T // A + 1 + T // B + 1 - T // C - 1)