#include <stdio.h>
#include <stdlib.h>
  
#define MAX 100
  
int pop();
void push(int);
  
int stack[MAX];
int top = 0;
  
int main(){
  
  int a, b, d;
  char c[7];
  
  while((scanf("%s", &c))!= EOF){
  
    if(c[0] == '+' || c[0] == '-' || c[0] == '*'){
  
      switch(c[0]){
  
      case '+':
        
    a = pop();
        
    b = pop();
        
    push(a + b);
        
    break;
  
  
      case '-':
        
    a = pop();
        
    b = pop();
  
    push(b - a);
  
    break;
  
  
      case '*':
       
    a = pop();
        
    b = pop();
  
    push(a * b);
  
    break;
  
  
      default:
  
    break;
      
      }
    }
  
    else{
  
      d = atoi(c);
  
      push(d);
  
    }
  
  }
  
  printf("%d\n", pop());
    
  return 0;
  
}
  
int pop(){
  
  if(top <= 0)
    return 0;
  else
    top = top - 1;
  
  
  return stack[top + 1];
   
}
  
void push(int data){
  
  top++;
    
  stack[top] = data;
    
}