在电脑上编译能正常运行，洛谷全WA，不知道什么原因，求助各位大佬

#include<iostream>
#include<vector>
using namespace std;
int main() {
    int n;
    cin >> n;
    int a,cnt =0;
    vector<int> v;
    while (cin >> a) {
        v.push_back(a);

    }
    for (int i = 0; i < v.size(); ++i) {
        for (int j = 0; j < v[i]; ++j) {
            if ((i + 1) % 2 != 0) {
                cout << 0; 
            }
            else {
                cout << 1;
            }
            cnt++;
            if (cnt % 7 == 0) {
                cout << "\n";
            }
        }
    }
}