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

int top = 0, S[1000];

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

int pop(void){
 top--;
 return S[top+1];
}

int main(void){
 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;
}
