import sys; input = sys.stdin.buffer.readline
sys.setrecursionlimit(10**7)
from collections import defaultdict
con = 10 ** 9 + 7; INF = float("inf")

def getlist():
	return list(map(int, input().split()))

#処理内容
def main():
	N = int(input())
	C, V = getlist()
	DP = [INF] * (2 * N + 1)
	DP[1] = 0
	for i in range(1, N):
		for j in range(2, N + 1):
			if i * j <= 2 * N:
				DP[i * j] = min(DP[i * j], DP[i] + C + V * (j - 1))
			else:
				break

	ans = INF
	for i in range(N, 2 * N + 1):
		ans = min(ans, DP[i])

	print(ans)

if __name__ == '__main__':
	main()