{$mode delphi}
{$r+}
unit stack_array;

interface

type
  stack = record
    a: array of integer;
    n: integer;
  end;

procedure init(var s: stack);
procedure push(var s: stack; i: integer);
function pop(var s: stack): integer;
function isEmpty(s: stack): boolean;

implementation

procedure init(var s: stack);
begin
  setLength(s.a, 1);
  s.n := 0;
end;

procedure push(var s: stack; i: integer);
begin
  if length(s.a) = s.n then
    setLength(s.a, length(s.a) * 2);
  s.a[s.n] := i;
  s.n := s.n + 1;
end;

function pop(var s: stack): integer;
begin
  pop := s.a[s.n - 1];
  s.n := s.n - 1;
end;

function isEmpty(s: stack): boolean;
begin
  isEmpty := (s.n = 0);
end;

end.

uses character, sysutils, stack_array;

procedure error(s: string);
begin
  writeln(s);
  halt;
end;

function readChar(): char;
begin
  if seekEoln then error('Chyba!');
  read(readChar);
end;

function isOp(c: char): boolean;
begin
  case c of
    '+', '-', '*', '/': exit(true);
    else exit(false);
  end;
end;

function evalOp(c: char; i, j: integer): integer;
begin
  case c of
    '+': exit(i + j);
    '-': exit(i - j);
    '*': exit(i * j);
    '/': exit(i div j);
  end;
end;

function evalPostFix():integer;
var
  c: char;
  i, j: integer;
begin
  c := readChar();
  if isDigit(c) then exit(strToInt(c));
  i := evalPrefix();
  j := evalPrefix();
  if not isOp(c) then error('Chyba!');
    exit(evalOp(c, i, j));
end;

begin
while not eof do
read(c);
if isOp(c) then evalOp(c);
writeln(evalPostFix());
end.