MPRIME Pascal

procedure nhap;
begin
    read(k);
end;
function ktnt(x:int64):boolean;
var i:longint;
begin
    if x<2 then exit(false);
    for i:=2 to trunc(sqrt(x)) do
        if x mod i=0 then exit(false);
    exit(true);
end;

procedure sang;
var i,j:longint;
begin
    m:=0;
    for i:=1 to max do p[i]:=true;
    p[1]:=false;
    for i:=2 to trunc(sqrt(max)) do
    begin
        if (p[i]=true) then
        begin
            j:=i+i;
            while j<=max do
            begin
                p[j]:=false;
                j:=j+i;
            end;
        end;
    end;
end;

procedure mang_a;
begin
        z:=1;
      //  writeln(max);
        for i:=1 to max do
        begin
                if p[i]=true then
                begin
                        a[z]:=i;
                        inc(z);
                end;
        end;
end;

function ghep(x,y:int64):int64;
var y1:int64;
begin
        y1:=y;
        while y>0 do
        begin
                y:=y div 10;
                x:=x*10;
        end;
        exit(x+y1);
end;
procedure giai;
begin
        d:=0;
     //   writeln(z);
        for i:=1 to z div 2 do
        begin
                        t:=ghep(a[i*2-1],a[i*2]);
                     //   writeln(t);
                        co:=false;
                        if t<max then
                                begin
                                if p[t]=true then co:=true ;
                                end
                        else
                                if ktnt(t)=true then co:=true;
                        if co=true then
                        begin
                                inc(d);
                                if d=k then
                                begin
                                        writeln(t);
                                        exit;
                                end;
                        end;
        end;
end;
begin
    assign(input,'MPRIME.inp');reset(input);
    assign(output,'MPRIME.out');rewrite(output);
    nhap;
    sang;
    mang_a;
    giai;
//write(d);
end.