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

int top = 0, st[2005];

void push(int val) {
  st[++top] = val;
}

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

int main() {
  int a, b;
  char s[105];
  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;
}

