#include <stdio.h>
#include <stdlib.h>
 
int main() {
  int i = 0;
  char s[7];
  char c;
  long a[100],temp;
 
  while(scanf("%s ", s) > 0) {
    c = s[0];
    if(c<'0' || c>'9') {
      switch (c) {
      case '+':
    temp = a[i-2] + a[i-1];
    break;
      case '-':
    temp = a[i-2] - a[i-1];
    break;
      case '*':
    temp = a[i-2] * a[i-1];
    break;
      default:
    break;
      }
      a[i-2] = temp;
      i = i-1;
    }else{
      a[i] = atol(s);
      i++;
    }
  }
  printf("%ld\n", a[0]);
 
  return 0;
}