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

int top, S[1000];

void push(int x) {
/* top ?????????????????????????????????????????\ */
  S[++top] = x;
}

int pop() {
  top--;
/* top ??????????????????????´?????????? */
  return S[top+1];
}

int main() {
  int a, b;
  char s[100];
  top = 0;
  
  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;
}