#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
stack<ll> st;
int main()
{
	ll cnt=0;
	string c;
	while(cin>>c)
	{
		if(c[0]>='0'&&c[0]<='9'){
			int ans=0;
			for(int i=c.size()-1;i>=0;i--) ans=ans*10+c[i];
			st.push(ans);
		}
		else
		{
			ll y=st.top();
			st.pop();
			ll x=st.top();
			st.pop();
			if(c[0]=='+')
				st.push(x+y);
			else if(c[0]=='-')
				st.push(x-y);
			else if(c[0]=='*')
				st.push(x*y);
		}
	}
	cout<<st.top();
	return 0;
}