#include <iostream>
#include <vector>

using namespace std;

int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(0);

    //cout << (int)'0';
    vector<int> a;
    string s, t, k;
    int c, d, e;
    getline(cin, s);
    for (int i = 0; i < (int)s.size(); i++) {
        if (s[i] == ' ')
            continue;
        if ((s[i] == '+') || (s[i] == '-') || (s[i] == '*')) {
            c = a.back();
            a.pop_back();
            d = a.back();
            a.pop_back();

            if (s[i] == '+')
                e = c + d;
            if (s[i] == '-')
                e = d - c;
            if (s[i] == '*')
                e = c * d;


            a.push_back(e);
        }
        if ((s[i] >= '0') && (s[i] <= '9')) {
            while (i < (int)s.size() && (s[i] >= '0') && (s[i] <= '9')) {
                t += s[i];
                ++i;
            }
            k = t;
            a.push_back(stoi(k));
            t = "";
        }
    }
    cout << a[0];
}

/*
8 9 + 1 7 - *
*/