I have a file which is made up of unknown rows but 2 columns and I would like to read this to a 2d vector, but I cannot achieve it, as my code skips the first columns all the time, i dont know why

I have written the code as follows:

```
#include <iostream>
#include <fstream>
#include <vector>
// this is for file handleing

using namespace std;

int main()
{
    ifstream fp("test3_r.txt");

    std::string token;

    vector< vector<int> > vt1;

    int x = 0;

    char split_char = ' ';

    int i =0;

    std::vector<int> inner_vector;

    while (std::getline(fp, token,split_char))
    {
        inner_vector.push_back(stoi(token));
        if(i%2==1)
        {
            vt1.push_back(inner_vector);
            inner_vector.clear();
        }
        i++;

    }

    for (int i = 0; i < vt1.size(); i++)
{
    for (int j = 0; j < vt1[i].size(); j++)
    {
        cout << vt1[i][j];
        cout << " ";

    }
    std::cout<<"\n";
}

    fp.close();
    return 0;
} 

```

example of my input file:

```
0 3
0 7
0 10
0 16
0 23
0 25
0 26
0 28
0 30
1 17
1 18
2 18
2 25
3 0
3 10
3 11
3 16
3 19
3 25
3 28
3 31
4 10
4 18
4 25
5 0
5 9
5 10
5 11
5 16
5 18
5 23
5 25
5 28
6 0
6 1
6 4
6 9
6 10
6 11
6 12
6 15
6 16
6 18
6 23
6 25
6 27
6 28
6 30
7 0
7 18
7 22
7 23
7 25 

```

The output i get is:

```
0 3 
7 10 
16 23 
25 26 
28 30 
17 18 
18 25 
0 10 
11 16 
19 25 
28 31 
10 18 
25 0 
9 10 
11 16 
18 23 
25 28 
0 1 
4 9 
10 11 
12 15 
16 18 
23 25 
27 28 
30 0 
18 22 
23 25  

```

Which is not what i want. any help is appreciated