c++ 我真的服了，为啥在vs上至少能正确出样例，这里提交之后0分

#include<iostream>
using namespace std;
int main()
{
    string a;
    string end = "0123456789X";
    cin >> a;
    int sum = 0;
    int j = 1;
    for (int i = 0; i < 12; i++)
    {
        if (a[i] == '-') continue;
        sum += (a[i] - '0') * j;
        j = j++;
    }
    if (a[12] == end[sum % 11 ]) cout << "Right" << endl;
    else {
        a[12] = end[sum % 11 ]; cout << a << endl;
    }
    return 0;
}