#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;
}