#include<iostream>

#include<stack>

#include<string>

#include<stdlib.h>

using namespace std;

int main(){

?string s;

?getline(cin,s);

?string temp="";

?int n,i,n1,n2,r;

?stack<int> t;

?n=s.length();

?for(i=n-1;i>=0;i--){

? if(isdigit(s[i])||s[i]=='-')

? temp+=s[i];

? if((isdigit(s[i])||s[i]=='-')&&(s[i-1]=='('||s[i-1]==')'||s[i-1]==',')){

? int num;

? num=atoi(temp.c_str());

? t.push(num);

? temp="";

}

if(isalpha(s[i]))

temp+=s[i];

if(isalpha(s[i])&&!isalpha(s[i-1])){

if(temp=="add"){

n1=t.top();t.pop();

n2=t.top();t.pop();

r=n1+n2;

t.push(r);

}else if(temp=="sub"){

n1=t.top();t.pop();

n2=t.top();t.pop();

r=n1-n2;

t.push(r);

}else if(temp=="div"){

n1=t.top();t.pop();

n2=t.top();t.pop();

r=n1/n2;

t.push(r);

}else if(temp=="mul"){

n1=t.top();t.pop();

n2=t.top();t.pop();

r=n1*n2;

t.push(r);

}

}

?}

?cout<<t.top()<<endl;

?return 0;

}