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

int top, N[100];

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

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

int main()
{

  char n[100];
  int a, b, top=0;

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

  return 0;
}