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;
}