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

int top, S[1000];

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

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

int main(void) {
  int a, b;
  top = 0;
  char s;

  while ( scanf("%s", &s) != EOF) {
    if (s == '+') {
      a = pop();
      b = pop();
      push(a + b);
    } else if (s == '-') {
      b = pop();
      a = pop();
      push(a - b);
    } else if (s == '*') {
      a = pop();
      b = pop();
      push(a * b);
    } else {
      push(atoi(&s));
    }
  }

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

  return 0;
}

