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

int top;
int s[1000];

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

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

int main(void)
{
  int a, b;
  top = 0;
  char v[200];
  
  while (scanf("%s", v) != EOF) {
    if (v[0] == '+') {
      a = pop();
      b = pop();
      push(a + b);
    } else if (v[0] == '-') {
      a = pop();
      b = pop();
      push(b - a);
    } else if (v[0] == '*') {
      a = pop();
      b = pop();
      push(a * b);
    } else {
      push(atoi(v));
    }
  }
  printf("%d\n", pop());

  return 0;
}

