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

LA1 = []
LB2 = []

X1 = 0
while X1 * A <= N:
    LA1.append(X1 * A)
    X1 += 1

X2 = 0
while X2 * B <= N:
    LB2.append(X2 * B)
    X2 += 1

bad = set(LA1) | set(LB2)

print(N + 1 - len(bad))