#include <bits/stdc++.h>
#define int long long
using namespace std;

int fn(char c, int a, int b) {
	if (c == '+')
		return a + b;
	if (c == '-')
		return a - b;
	if (c == '*')
		return a * b;
}

inline bool isNum(char c) {
	return c >= '0' && c <= '9';
}

signed main() {
	string s;
	getline(cin, s);
	stack<int> stk;
	for (int i = 0; i < s.size(); i += 2) {
		for (int sum, p = 1; isNum(s[i]) || s[i] == '-' && isNum(s[i + 1]); stk.push(sum * p), i++, p = 1) {
			if (s[i] == '-')
				p = -1, i++;
			for (sum = 0; isNum(s[i]); i++)
				sum = sum * 10 + s[i] - '0';
		}
		int b = stk.top();
		stk.pop();
		int a = stk.top();
		stk.pop();
		stk.push(fn(s[i], a, b));
	}
	cout << stk.top();
	return 0;
}