[Boost-users] Question about network flow examples

Greetings, On the edmunds-karp-eg.cpp and the push-relabel-eg.cpp, the output is is as shown below. But I dont understand how in the first flow describing line "f 0 6 3" is listed since there is not vertex with id 0. The vertices are labeled from 1 to N as I understand. Even the input file max_flow.dat in the examples folder labels the vertices from 1..N. thanx // Sample output: // c The total flow: // s 13 // // c flow values: // f 0 6 3 // f 0 1 0 // f 0 2 10 // f 1 5 1 // f 1 0 0 // f 1 3 0 // f 2 4 4 // f 2 3 6 // f 2 0 0 // f 3 7 5 // f 3 2 0 // f 3 1 1 // f 4 5 4 // f 4 6 0 // f 5 4 0 // f 5 7 5 // f 6 7 3 // f 6 4 0 // f 7 6 0 // f 7 5 0