zz

#include<bits/stdc++.h>
using namespace std;

#define mx 10000


int a[mx];
int tp=-1;

int Push(int x)
{
    if(tp==mx-1)
    {
        cout<<"Stack overflow"<<endl;
        return 0;
    }
    else
        a[++tp]=x;
}
void Pop()
{
    if(tp==mx-1)
    {
        cout<<"No element to print"<<endl;
        return;
    }
    tp--;
}
int Top()
{
    return a[tp];
}
bool Empty()
{
    if(tp==-1)
        return true;
    else return false;
}

bool isoperator(char c)
{
    if(c=='+'||c=='-'||c=='/'||c=='*')
        return true;
    return false;
}
bool isoperand(char c)
{
    if((c>='0'&&c<='9')||(c>='a'&&c<='z')||(c>='A'&&c<='Z'))
        return true;
    return false;
}
int perform(char c,int o1,int o2)
{
    switch(c)
    {
    case '+':
        return  o1+o2;
    case '-':
        return o1-o2;

    case '*':
        return o1*o2;
    case '/':
        return o1/o2;
    }
}
int prefix_evaluation(string s)
{
    int op1,op2,result;
    for(int i=s.size()-1; i>=0; i--)
    {
        if(s[i]==' '||s[i]==',') continue;
        else if(isoperand(s[i]))
        {
            int operand=0,x=1;
            while(i<s.size()&&isoperator(s[i]))
            {
                operand=operand+(s[i]-'0')*x;
                i--;
                x*=10;
            }
            Push(operand);
            i++;
        }
        else if(isoperator(s[i]))
        {
            op1=Top(); Pop();
            op2=Top(); Pop();
            result= perform(s[i],op1,op2);
            Push(result);
        }
    }
    return Top();
}

int main()
{
    string s;
    getline(cin,s);
    int x= prefix_evaluation(s);
    cout<<"result= "<<x<<endl;
    /**
    - + * 2 3 * 5 4 9
    **/
}