我不会Markdown

传送门，非洛谷

代码：

#include<cstring>
#include<iostream>
using namespace std;
int main(){
    int sum=0;
    char ch[100];
    cin >> ch;
    int len=strlen(ch);
    sum=ch[0]-'0';
    for(int i=0;i<len;i++){
        switch (ch[i])
        {
        case '+':
            sum+=(ch[i-1]-'0');
            break;
        case '-':
            sum-=(ch[i-1]-'0');
            break;
        case '*':
            sum*=(ch[i-1]-'0');
            break;
        case '/':
            sum=(ch[i-1]-'0')/sum;
            break;
        default:
            break;
        }
    }
    cout << sum;
    return 0;

}

丑陋的代码，丑陋的Oier