program Proga;

const
  Chisla: set of Char = ['0', '1','2','3','4','5','6','7','8','9'];
  Znaki: set of Char = ['+','-','*'];

type
bt = string;
  Adr = ^Derevo;
  Derevo = record
             L: Adr;
             R: Adr;
             Inf: Integer;
           end;

var
  TextFile: Text;
  Der1, Der2: Adr;
  Dat: bt;
  N: Integer;
  A1: Integer;

function Pered(TT: Adr; var  N: Integer): Adr;
var
  C: Char;
  D, X: Integer;
const
  A: bt = '';
begin
if N <= Length(Dat) then
begin
  A := '';
  Inc(N);
  C := Dat[N];
  if C in Chisla then
  begin
    D := N;
    while (Dat[D] in Chisla) and (D <= Length(Dat)) do
    begin
      A := A + Dat[D];
      Inc(D);
    end;
    if D - 1 = N then
      A := Dat[N];
    Val(A, A1, X);
    N := D;
    TT^.L := nil;
    TT^.R := nil;
    TT^.Inf := A1;
  end
  else
  begin
    TT^.L := Pered(TT^.L, N);
    if Dat[N] = '-' then
      TT^.Inf := -1
    else
    if Dat[N] = '+' then
      TT^.Inf := -2
    else
    if Dat[N] = '*' then
      TT^.Inf := -3;
    TT^.R := Pered(TT^.R, N);
  end;
end;
end;

function Rezult(Tree: Adr): Integer;
var
  B: Integer;
begin
  if Tree^.L = nil then
    Rezult := Tree^.Inf
  else
  begin
    case Tree^.Inf of
      -1: Rezult := Rezult(Tree^.L) - Rezult(Tree^.R);
      -2: Rezult := Rezult(Tree^.L) + Rezult(Tree^.R);
      -3: Rezult := Rezult(Tree^.L) * Rezult(Tree^.R);
    end;
  end;
end;

begin
  Assign(TextFile, 'D:\Work\TextFile.txt');
  Reset(TextFile);
  New(Der1);
  New(Der2);
  Der1 := nil;
  Der2 := Der1;
  Readln(TextFile, Dat);
  N := 0;
  Pered(Der1, N);
  Writeln(Rezult(Der1));
end.