N = int(input())
C, V = map(int, input().split())
INF = 10 ** 8
D = [INF] * (N + 1)
D[1] = 0
for i in range(1, N):
    j = 0
    while i * j < N:
        j += 1
        D[min(i + i * j, N)] = min(D[min(i + i * j, N)], D[i] + C + V * j)
print(D[N])