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