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

int top,S[1000];

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

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

  return 0;

}
