class Solution {
public:
    int firstCompleteIndex(vector<int>& arr, vector<vector<int>>& mat) {
        int m = mat.size(), n = mat[0].size();
        vector<int> flag1(m, 0);
        vector<int> flag2(n, 0);
        int len = arr.size();
        int map[len];
        for (int i = 0; i < m; i++) {
            for (int j = 0; j < n; j++) {
                map[mat[i][j]-1] = i*n + j;
            }
        }
        int ret = 0, temp, mm, nn;
        for (int i = 0; i < len; i++) {
            temp = map[arr[i]-1];
            mm = temp / n, nn = temp % n;
            flag1[mm]++, flag2[nn]++;
            if (flag1[mm] == n || flag2[nn] == m) {
                ret = i;
                break;
            }
        }
        return ret;
    }
};