#include <iostream>
#include <cstdlib>
#include <string>
#include <algorithm>
#include <vector>
#include <stack>
#include <queue>
using namespace std;
int evalRPN(vector<string> &tokens) {
stack<int> value;
int i = 0;
for(i = 0; i < tokens.size(); i++){
if(tokens[i] == "+" || tokens[i] == "-" || tokens[i] == "*" || tokens[i] == "/"){
string t = tokens[i];
int a = value.top();
value.pop();
int b = value.top();
value.pop();
if(t == "+"){
value.push(b + a);
}
if(t == "-"){
value.push(b - a);
}
if(t == "*"){
value.push(b * a);
}
if(t == "/"){
value.push(b / a);
}
}else{
value.push(atoi(tokens[i].c_str()));
}
}
return value.top();
}
int main(int argc, char** argv) {
vector<string> s;
s.push_back("4");
s.push_back("13");
s.push_back("5");
s.push_back("/");
s.push_back("+");
cout<<evalRPN(s);
return 0;
}