write a c++ parser using nlohmann of this json:
{
    "componentSets": {},
    "components": {},
    "document": {
        "children": [
            {
                "backgroundColor": {
                    "a": 1.0,
                    "b": 0.9607843160629272,
                    "g": 0.9607843160629272,
                    "r": 0.9607843160629272
                },
                "children": [
                    {
                        "absoluteBoundingBox": {
                            "height": 424.0,
                            "width": 433.0,
                            "x": -347.0,
                            "y": -286.0
                        },
                        "absoluteRenderBounds": {
                            "height": 424.0,
                            "width": 433.0,
                            "x": -347.0,
                            "y": -286.0
                        },
                        "background": [],
                        "backgroundColor": {
                            "a": 0.0,
                            "b": 0.0,
                            "g": 0.0,
                            "r": 0.0
                        },
                        "blendMode": "PASS_THROUGH",
                        "children": [
                            {
                                "absoluteBoundingBox": {
                                    "height": 100.0,
                                    "width": 100.0,
                                    "x": -347.0,
                        The letter z should appear at least 25 times.
user