#include<bits/stdc++.h>
using namespace std;
int main(){
	stack<char> a;
	char w;
	int n=0,m=0,y=0;
	cin>>w;
	do{
		if(w=='/' || w=='*' || w=='-' || w=='+'){
			n=a.top()-'0';
			a.pop();
			m=a.top()-'0';
			a.pop();
			if(w=='/'){
				y=n/m;
				a.push(y+'0');
			}else if(w=='*'){
				y=n*m;
				a.push(y+'0');
			}else if(w=='-'){
				y=n-m;
				a.push(y+'0');
			}else{
				y=n+m;
				a.push(y+'0');
			}
		}else if(w=='.'){
			/*37*/
		}else{
			a.push(w);
		}
		cin>>w;
	}while(w=='@');
	cout<<a.top()-'0';
	return 0;
}

实在写不出了，dalao们救救我