import std.stdio, std.string, std.conv
	,std.array,std.algorithm, std.range
	,std.math;

void main(){
	auto buf = readln().strip().split().map!(to!int)();
  immutable int N = buf[0];
  immutable int D = buf[1];
  immutable int T = buf[2];

	auto x = readln().strip().split().map!(to!int)();
  auto X = x.array.sort();

  int[][int] sd;

  foreach(int xe; X) {
    sd[xe%D] ~= xe/D;
  }

  long ans = 0;

  foreach(int[] s; sd) {
    ans += s.length * (2 * T + 1);
    foreach(immutable int i; 0 .. s.length.to!int - 1) {
      if(s[i] + T >= s[i+1] - T) {
        ans -= s[i] + T - (s[i+1] - T) + 1;
      }
    }
  }

  writeln(ans);
}