#include <iostream>
#include <algorithm>
#include <unordered_map>
using namespace std;
int main()
{
    int n, d, t;
    while (cin>>n>>d>>t) {
        vector<int> x(n);
        for(int& v: x) cin>>v;
        sort(begin(x), end(x));
        for(int i=1;i<n;++i) x[i]-=x[0];
        x[0]=0;

        unordered_map<int, vector<int>> a;
        for(int v: x) a[v%d].push_back(v/d);
        
        long long res=0;
        for(auto& v: a) {
            auto& w=v.second;
            res+=2*t+1;
            for(int i=1;i<w.size();++i)
                res+=2*t+1-max(0, w[i-1]+t+1-(w[i]-t));
        }
        cout<<res<<endl;
    }
}