#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];
  return S[top--];
}

int main()
{
  int a,b;
  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 push(atoi(s));
  }

  printf("%d\n", pop());

  return 0;
}

