#include <stdio.h>
int stack[1005];
int stack_size = 0;
int pop()
{
  if(stack_size <= 0) return 0;
  return stack[--stack_size];
}
int push(int a)
{
  stack[stack_size++] = a;
}
int is_digit(char *s)
{
  if(*s == '+' || *s =='-'){
    s++;
    if(*s >= '0' && *s <= '9') return 1;
    return 0;
  }
  if(*s >= '0' && *s <= '9') return 1;
  return 0;
}
int get_number(char *s)
{
  int sign = 0, n = 0;
  if(*s == '+'){
    s++;
  }
  else if(*s == '-'){
    sign = 1;
    s++;
  }
  while(*s >= '0' && *s <= '9'){
    n = n * 10 + (*s - '0');
    s++;
  }
  if(sign) return -n;
  return n;
}
int calc_rpn(char *s)
{
  int a, b, n;
  while (*s){
    if(is_digit(s)){
      n = get_number(s);
      push(n);
      while (*s == '-' || *s == '+') {
	s++;
      }
      while (n) {
	n /= 10;
	s++;
      }
    }
    else {
      switch (*s) {
      case '+':
	a = pop();
	b = pop();
	push(b+a);
	break;
      case '-':
	a = pop();
	b = pop();
	push(b-a);
	break;
      case '*':
	a = pop();
	b = pop();
	push(b*a);
	break;
      case '/':
	a = pop();
	b = pop();
	if (a == 0)
	  break;
	push(b/a);
	break;
      }
      s++;
    }
  }
  return pop();
}
int main()
{
  char s[1005];
  int r;
  scanf("%[^\n]*s", s);
  printf("%d\n",calc_rpn(s));
 
  return 0;
}

