Cut a triangulated surface mesh by seam and planar parameterization of this mesh,how to write the vertices to off in the original order?

Question

This is a standard plane mesh OFF file(standard_plane_mesh.off):

OFF
36 50 0
0 0 0 
0 1 0 
0 2 0 
0 3 0 
0 4 0 
0 5 0 
1 0 0 
1 1 0 
1 2 0 
1