#include<stdio.h>

#include<vector>

#include<stack>

#include<string>

using namespace std;

class Solution {

public:

int evalRPN(vector<string>& tokens) {

stack<int> works;

for (int i = 0; i < tokens.size(); ++i) {

const string& s = tokens[i];

if (s.length() == 1) {

int a;

int b;

switch (s.c_str()[0]) {

#define GETVALUES b = works.top(); works.pop(); a = works.top(); works.pop();

#define SETVALUE(x) works.push(x);

case '+':

GETVALUES;

SETVALUE(a+b);

break;

case '-':

GETVALUES;

SETVALUE(a-b);

break;

case '*':

GETVALUES;

SETVALUE(a*b);

break;

case '/':

GETVALUES;

SETVALUE(a/b);

break;

default:

SETVALUE(stoi(s));

break;

}

} else {

SETVALUE(stoi(s));

}

}

return works.top();

}

};

int main()

{

vector<string> in;

Solution s;

#if 0

in.push_back("2");

in.push_back("1");

in.push_back("+");

in.push_back("3");

in.push_back("*");

#endif

#if 1

in.push_back("4");

in.push_back("13");

in.push_back("5");

in.push_back("/");

in.push_back("+");

#endif

printf("%d\n", s.evalRPN(in));

return 0;

}