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

void push(int);
int pop();
 int top, S[1000];

int main(){
  int x,y;
  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 {
      push(atoi(s));
    }
    
  }

  printf("%d\n",pop());
  
  return 0;
}

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

int pop(){
  top--;

  return S[top+1];
}

