#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;
  char s[100];
  top = 0;

  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 push(atoi(s));
    }
  printf("%d\n",pop());

  return 0;
}

