[
    { "from": 1, "to": 2 },
    { "from": 1, "to": 3 },
    { "from": 2, "to": 3 },
    { "from": 4, "to": 5 },
    { "from": 4, "to": 6 },
    { "from": 4, "to": 7 },
    { "from": 5, "to": 6 },
    { "from": 5, "to": 7 },
    { "from": 6, "to": 7 },
    { "from": 8, "to": 9 }
]