import sys

def main():
    input = sys.stdin.readline
    
    n, a, b = map(int, input().split())
    
    f = 0
    c = 11 * 9 * 8 * 7 * 5  
    
    for i in range(n + 1):
        k = int(input())
        s = b ** (i + 1) * k * c // (i + 1)
        t = a ** (i + 1) * k * c // (i + 1)
        f = f + s - t
        
    print(f // c)


if __name__ == "__main__":
    main()