#include <iostream>

#include <vector>

#include <string>

using namespace std;

int main(){

vector<int> stack;

//stack.push_back(1); these are for a vector to be a stack

//stack.back();

//stack.pop_back();

string s;

cin >> s;

//postfinx form numbers are only one character long

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

if(s[i] != '+' && s[i] != '-' && s[i] != '*' && s[i] != '/'){ //it's a number

//cout << int(s[i]) << endl;

stack.push_back(int(s[i])-48);

}

else{ //it's an action

if(stack.size() >= 2){ // we have what to work with

int tmp1 = stack.back();

stack.pop_back();

int tmp2 = stack.back();

stack.pop_back();

switch(s[i]){

case '+':

stack.push_back(tmp2 + tmp1);

break;

case '-':

stack.push_back(tmp2 - tmp1);

break;

case '*':

stack.push_back(tmp2 * tmp1);

break;

case '/':

stack.push_back(tmp2 / tmp1); //cd/ = c / d

break;

}

}

else{

cout << "you have problems in postfix form" << endl;

break;

}

}

}

if(stack.size() == 1) cout << stack.back() << endl;

else cout << "you have problems in postfix form, not enough actions";

//couple of tests

// ab+cd-* = (a+b)*(c-d)

// abc+d/* = a*((b+c)/d)

// ab-c*d- = (a-b)*c-d

return 0;

}