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

int stack_num, S[1000];

int main(){
  int a, b, x;
  char s[100];

  while( scanf("%s", s) != EOF ){
    if ( s[0] == '+' ){
      a = pop();
      b = pop();
      push(a+b);

    } else if ( s[0] == '-' ){
      b = pop();
      a = pop();
      push(a-b);
      
    } else if ( s[0] == '*' ){
      a = pop();
      b = pop();
      push(a * b);
      
    } else {
      x = atoi(s);
      push(x);

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

void push(int x){

  S[++stack_num] = x;

}

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

}