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

int top, S[1000];

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

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] == '*') {
      b = pop();
      a = pop();
      push(a * b);
    } else {
      push(atoi(s));
    }
  }
  
  printf("%d\n", pop());
  
  return 0;
 }
