# 2次元dp
# dp[i番目][0 for -1, 1 for 1]での最小値

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

INF = 10**12
dp = [[INF]*2 for i in range(N)]
dp[0][0] = B
dp[0][1] = -B

for i in range(1, N):
    dp[i][0] = min(dp[i-1][0]+A+B, dp[i-1][1]-A+B)
    dp[i][1] = min(dp[i-1][0]-A-B, dp[i-1][1]+A-B)
    #print(dp[i])

ans = min(dp[N-1])
print(ans)