解法：

#include<iostream>
#include<stack>
using namespace std;
int main() {
	char a;
	stack<int> sk;
	while (cin >> a && a != '#') {
		if (a >= '0' && a <= '9') {
			sk.push(a - '0');
		}
		else {
			int num2 = sk.top();
			sk.pop();
			int num1 = sk.top();
			sk.pop();
			if (a == '*') sk.push(num1 * num2);
			if (a == '/') sk.push(num1 / num2);
			if (a == '+') sk.push(num1 + num2);
			if (a == '-') sk.push(num1 - num2);
		}
	}
	cout << sk.top();
	return 0;
}