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

// stack
int top, S[100000];
void push(int x) {
  S[++top] = x;
}
int pop() {
  top--;
  return S[top+1];
}

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();
      int tmp = a - b;
      push(a - b);
    } else if (s[0] == '*') {
      a = pop();
      b = pop();
      push(a * b);
    } else {
      push(atoi(s));
    }
  }

  printf("%d\n", pop());
  return 0;
}