uses crt;
var a: array[1..1000000] of longint;
    n,i,s,ans: longint;
begin
    assign(input, 'TEAM.INP'); reset(input);
    assign(output, 'TEAM.OUT'); rewrite(output);
    readln(n);
    for i := 1 to 1000000 do a[i] := 0;
    for i := 1 to n do begin
        read(s);
        inc(a[s]);
    end;
    ans := 0;
    for i := 1 to 1000000 do ans := ans + (a[i] div i);
    write(ans);
end.