N = int(input())
C,V = map(int,input().split())
INF = 1 << 60
dp = [INF] * (N + 1)
dp[1] = 0

for i in range(1, N + 1):
    if dp[i] != INF:
        for j in range(1, N + 1):
            if i + j * i > N:
                dp[N] = min(dp[N], dp[i] + C + j * V)
                break
            dp[i + j * i] = min(dp[i + j * i], dp[i] + C + j * V)
#    print("i",i,dp[1:])

print(dp[N])