#include<stdio.h>
#include<stdlib.h>
#include<string.h>
int pop();
void push(int);
int Stack[200],top;

int pop(){
  top--;
  return Stack[top+1];
}
void push(int x){
  Stack[++top] = x;
}


main()
{
  int x,a,b;
  char s[100];
  top = 0;
  while(scanf("%s", s) != EOF)
    {
      if(s[0] == '+')
	{
	  a = pop();
	  b = pop();
	  push(a+b);
	}
      else if(s[0] == '-')
	{
	  b = pop();
	  a = pop();
	  push(a-b);
	}
      else if(s[0] == '*')
	{
	  a = pop();
	  b = pop();
	  push(a*b);
	}
      else
	{
	  x = atoi(s);
	  push(x);
	}
    }
  printf("%d\n", pop());
  return 0;
}