#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;
}
