#include <bits/stdc++.h>

using namespace std;
bool isOp(string  c){
    return c == "+" || c == "-" || c == "*" || c == "/";
}
int eval(string s){
    stack<int> stk;
    stringstream s1(s);
    string c;
    while (s1>>c){
        if(isOp(c)){
            int a = stk.top();
            stk.pop();
            int b = stk.top();
            stk.pop();
            if (c == "+") stk.push(b + a);
            if (c == "-") stk.push(b - a);
            if (c == "*") stk.push(b * a);
            if (c == "/") stk.push(b / a);
        }else
            stk.push(stoi(c));
    }
    return stk.top();
}
int main() {
    string s = "24 9 6 3 / + 5 - * 4 +";
    cout << "answer:" << eval(s) << endl;
    return 0;
}