Program zombie;
  var t:array[1..1000005]of longint;
      s:string;
      p,i,cost,j,l,d,n,k:longint;
      f,g:text;

Function citire:longint;
  var aux:longint;
begin
  aux:=0;
  while(p<=l) and (s[p]>='0') and (s[p]<='9')do begin
                           aux:=aux*10+(ord(s[p])-48);
                           if(p=l)then begin
                              read(f,s);
                              l:=length(s);
                              p:=0;
                              end;
                           inc(p);
                          end;
  while (p<=l) and ((s[p]<'0') or (s[p]>'9')) do begin
                              inc(p);
                           if(p>l)then begin
                               read(f,s);
                               l:=length(s);
                               p:=1;
                              end;

                              end;
        citire:=aux;
        end;

Begin
  assign(f,'zombie.in'); reset(f); readln(f,d,n,k);
  read(f,s); p:=1; l:=length(s); cost:=0;
  for i:=1 to n do t[i]:=citire;
  i:=1;
  while(i<n) do begin
       j:=i+1;
       while(t[j]-t[i]<d) and (j<=n)do inc(j);
       if(k<j-i)then cost:=cost+k else cost:=cost+j-i;
       i:=j;
       end;
  assign(g,'zombie.out'); rewrite(g); write(g,cost); close(g);
end.