import math
from decimal import Decimal
import sys
input = sys.stdin.readline
N, A, B = map(int, input().split())
K = [int(input()) for _ in range(N+1)]

def F(x):
    ret = 0
    for i in range(N+1):
        ret += K[i]*x**(i+1)/(i+1)
    return ret

ans = F(Decimal(B))-F(Decimal(A))
print(math.floor(ans))