#include<stdio.h>
#include<stdlib.h>
#define MAX 101

int top;
int S[MAX];

void initialize()
{
  top = 0;
}

int isEmpty()
{
  return top == 0;
}

int isFull()
{  
  return top >= MAX - 1;
}

void push(int x)
{
  if (isFull()) {
    exit(1);
  }
             
  top++;
  S[top] = x;
}

int pop() {
  if (isEmpty()) {
    exit(1);
  }

  top--;
  return S[top+1];
}

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

  while( scanf("%s", s) != EOF ){
    if ( s[0] == '+' ){
      a = pop();
      b = pop();
      push(a+b);
    } else if ( s[0] == '-' ){
      a = pop();
      b = pop();
      push(b-a);
    } else if ( s[0] == '*' ){
      a = pop();
      b = pop();
      push(a*b);
    } else {
      x = atoi(s);
      push(x);
    }
  }
  
  printf("%d\n", pop());
  return 0;
}

