#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#define MAX 99
int top=0,S[1000000];
int pop();
void push(int);
int main()
{
  int x=0,a,b;
  char s[100];
  while(scanf("%s",s)!=EOF)
    {
      if(s[0] == '+')
	{
	  a=pop();
	  b=pop();
	  push(a+b);
	}
      else if(s[0] == '-')
	{
	  a=pop();
	  b=pop();
	  push(b-a);
	 	}
      else if(s[0] == '*')
	{
	  a=pop();
	  b=pop();
	  push(a*b);
	 	}
      else
	{
	  push(x=atoi(s));
	}
    }
  printf("%d\n",pop());
  return 0;
}
void push(int x)
{
       top++;
      S[top]=x;
 }
int pop()
{
       top--;
   return S[top+1];
}

