#include<stdio.h>
#include<stdlib.h>
#include<string.h>

int pop(void);
void push(int a);

int top,S[1000];

int main()
{
  int x=0,y=0;
  char s[100];


  while( scanf("%s",&s)!=EOF)
    {
      
      if(s[0]== '+'&& 1<=strlen(s)&& strlen(s)<=99){
	x=pop();
	y=pop();
	push(x+y);      
      }    

  
      else if(s[0]== '-' &&1<=strlen(s)&& strlen(s)<=99){
	x=pop();
	y=pop();
	push(y-x);      


      }

      else if(s[0]== '*'&& 1<=strlen(s)&& strlen(s)<=99){
	x=pop();
	y=pop();
	push(x*y);      
      }
      else push(atoi(s));
    }
  printf("%d\n",pop());
  return 0;

}
int pop(){
  top--;
  return S[top+1];
}

void push(int a){
  top++;
  S[top] = a;
}