import numpy as np
N, E, T = map(int, raw_input().split())
x = np.array(map(int, raw_input().split()))

dp = np.zeros(N, dtype='int')
for i in range(N):
    if i == 0:
        dp[i] = T
    else:
        dp[i] = (dp[0:i] + np.maximum(T, 2*(x[i] - x[1:(i+1)]))).min()

print dp[N-1] + E