2-25编写一个完整的程序，运行时向用户提问”你考试考了都少分？（0~100）”，接受输入后判断其等级显示出来。规则如下：

#include <iostream>
using namespace std;
int main() {
    cout << "你考试考了多少分？（0~100）" << endl;
    int score;
    cin >> score;
    if (90 <= score && score <= 100) {    //不能使用连续比较，跟数学不一样，比如a <= b <= c 应改为a<=b&&b<=c
        cout << "优" << endl;
    }
    else if (80 <= score && score < 90) {
        cout << "良" << endl;
    }
    else if (60 <= score && score < 80) {
        cout << "中" << endl;
    }
    else if (0 <= score && score < 60) {
            cout << "差" << endl;
        }
    return 0;
}