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

int top, S[1000];

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

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

int main()
{
  int a, b, x;
  top = 0;
  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;
}

