N,D,T=map(int,input().split())
A=list(map(int,input().split()))

DICT=dict()
for a in A:
    if a%D in DICT:
        DICT[a%D].append(a)
    else:
        DICT[a%D]=[a]

ANS=0
for k in DICT:
    L=DICT[k]
    L=sorted(set(L))
    ANS+=T+T+1

    for i in range(len(L)-1):
        #print(ANS)
        x=L[i]
        y=L[i+1]

        if (y-x)<=2*T*D+D:
            ANS+=(y-x)//D
        else:
            ANS+=2*T+1

print(ANS)