N,D,T=map(int,raw_input().split())
X=map(int,raw_input().split())
lists=[]
for x in X:
    lists.append((x%D,x))
lists.sort()
ans=N+T*2
for i in range(N-1):
    if lists[i][0] != lists[i+1][0]:
        ans += T*2
    elif lists[i+1][1]-lists[i][1] >= (2*T+1)*D:
        #print lists[i][j],'-',lists[i][j+1],"=",T*2
        ans += T*2
    else:
        #print lists[i][j],'-',lists[i][j+1],"=", (lists[i][j+1]-lists[i][j])/D-1
        ans += (lists[i+1][1]-lists[i][1])/D-1
print ans