#include<iostream>
#include<cstdio>
#include<cmath>
#include<cstring>
#include<string>
#include<vector>
#include<algorithm>
#include<ctime>
#include<cstdlib>
#include<stack>
using namespace std;
string s;
stack<int>z;
int a[55],n;
int main(){
	cin>>s;
	int len=s.size();
	string ss;
	for(int i=0;i<len;i++){	
		if(a[i]=='@') break;
		if(a[i]>='0'&&a[i]<='9'){
			n=n*10+a[i]-'0';
		}
		else if(a[i]=='.'){
			z.push(n);
			n=0;
		}
		else{
			int x,y,t;
			x=z.top();
			z.pop();
			y=z.top();
			z.pop();
			if(a[i]=='+') t=x+y;
			else if(a[i]=='-') t=y-x;
			else if(a[i]=='*') t=x*y;
			else if(a[i]=='/') t=y/x;
			z.push(t);
		}	
	}
	printf("%d",z.top());
	return 0;
}