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

int top = 0;
int stack[100];

void push(int x) {
  top++;
  stack[top-1] = x;
}

int pop() {
  top--;
  return stack[top];
}

int main() {
  char s[7];
  int a, b;

  while ( scanf("%s", s) != EOF ) {
    if ( s[0] == '+' ) {
      push(pop() + pop());
    } else if ( s[0] == '-' ) {
      b = pop();
      a = pop();
      push(a - b);
    } else if ( s[0] == '*' ) {
      push(pop() * pop());
    } else {
      push(atoi(s));
    }
  }

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

  return 0;
}

