How to get the checkbox checked row data in datagrid view by using button click(outside of grid)

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;

namespace WindowsFormsApplication2
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        List<int> CheckBoxChecked = new List<int>();

        private void Form1_Load(object sender, EventArgs e)
        {
            dataGridView1.RowCount = 10;
            int i = 0;
            // Creating a test data
            foreach (DataGridViewRow Row in dataGridView1.Rows)
            {
                i++;
                Row.Cells[0].Value = i;
                Row.Cells[1].Value = i+10;

                if (i % 2 == 0) // Assigning Checked to cells whose col 1 is divisible by 2
                {
                    DataGridViewCheckBoxCell dgvcbcell = (DataGridViewCheckBoxCell) Row.Cells[2];

                    dgvcbcell.Value = true;
                }
            }

        }

        private void BtnSubmit_Click(object sender, EventArgs e)
        {
            foreach (DataGridViewRow Row in dataGridView1.Rows)
            {
                DataGridViewCheckBoxCell dgvcbcell = (DataGridViewCheckBoxCell)Row.Cells[2];

                if (true == dgvcbcell.EditedFormattedValue)
                {
                    CheckBoxChecked.Add(Row.Index+1);//Actual count is Index + 1 since index satrts from 0
                }
            }
        }
    }
}