How should I read a simple .txt file?

I have my file.txt. It looks like this:

1 43.8
3 34.5
4 23.0
5 34.3

I want to read it and make a root function or histogram.
How can I do this with ROOT in a simplest way?

TGraph g("file.txt"); g.SetMarkerStyle(21); g.Draw("alp");