3v4l.org

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<?php print_r(array_keys((array)json_decode(/* 0 */ '{ "0" : 3870, "1" : 2580, "2" : 6450, "3" : 3225, "4" : 5160, "5" : 4515, "6" : 5805, "7" : 9675, "8" : 7095, "9" : 10320, "10" : 9030, "11" : 7740, "12" : 8385, "13" : 12900, "14" : 1290, "15" : 0, "16" : 10965, "17" : 15480, "18" : 5960, "19" : 1935, "20" : 4470, "21" : 5215, "22" : 3725, "23" : 2980, "24" : 11610, "25" : 12255, "26" : 2258, "27" : 5483, "28" : 2235, "29" : 7450, "30" : 1490, "31" : 4193, "32" : 6705, "33" : 5588, "34" : 7823, "35" : 12665, "36" : 8940, "37" : 8195, "38" : 323, "39" : 16390, "40" : 9685, "41" : 2903, "42" : 10430, "43" : 13545, "44" : 4843, "45" : 15645, "46" : 11920, "47" : 373, "48" : 13410, "49" : 2608, "50" : 8568, "51" : 4838, "52" : 4098, "53" : 11175, "54" : 14155, "55" : 14900, "56" : 745 }')));

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34.54 ms | 402 KiB | 5 Q