Why is input number non-existent in bitcoin API? Why when I use this public Bitcoin Api to practice a command, the input value of BTC does not show up? 

API Call can be found here:

API Website

Transaction from block explorer can be found here:

Explorer Tx

{
    "result": {
        "txid": "1e12864a9852ebd2b71a743752cc1561b000663f47bd71bc383b0cacad614d86",
        "hash": "bf43137e355def3d6292c296c864d9f6a9da353db6e4bd40c55e7cc4df245774",
        "version": 2,
        "size": 249,
        "vsize": 168,
        "locktime": 0,
        "vin": [
            {
                "txid": "9de8923855b2c56bc903c39418298fa8c185e5feb99cb32bfa31b9d06700ced8",
                "vout": 1,
                "scriptSig": {
                    "asm": "00140b67d98b0069797e0b5c94964f94d69476bea509",
                    "hex": "1600140b67d98b0069797e0b5c94964f94d69476bea509"
                },
                "txinwitness": [
                    "30440220625b6fd7299cfd14e6bdaa63cef809da54d4016c6caf5d268fc80c48d7fb41cc02200da35a319d63926112aa26952933ce590e67023993072ab10ab2bfb44f55704f01",
                    "03c97015da537daded1ac5fd4b5f9cfe55d1d77aed63da77da097d2af087361339"
                ],
                "sequence": 4294967295
            }
        ],
        "vout": [
            {
                "value": 1.99550000,
                "n": 0,
                "scriptPubKey": {
                    "asm": "OP_DUP OP_HASH160 b0fe30da6628923202cbf6e877405ea6d484e9eb OP_EQUALVERIFY OP_CHECKSIG",
                    "hex": "76a914b0fe30da6628923202cbf6e877405ea6d484e9eb88ac",
                    "reqSigs": 1,
                    "type": "pubkeyhash",
                    "addresses": [
                        "1H8rSFYmaZoSbdsXjF4Q5zb53FHNYAdTLj"
                    ]
                }
            },
            {
                "value": 82.88960000,
                "n": 1,
                "scriptPubKey": {
                    "asm": "OP_HASH160 fe7dfeeb1cbf6330590bc7ee2c47a2de593f1920 OP_EQUAL",
                    "hex": "a914fe7dfeeb1cbf6330590bc7ee2c47a2de593f192087",
                    "reqSigs": 1,
                    "type": "scripthash",
                    "addresses": [
                        "3QteVcFbTqoS8fSFYgwuet1yWD8YGfuas4"
                    ]
                }
            }
        ],
        "hex": "02000000000101d8ce0067d0b931fa2bb39cb9fee585c1a88f291894c303c96bc5b2553892e89d01000000171600140b67d98b0069797e0b5c94964f94d69476bea509ffffffff0230e4e40b000000001976a914b0fe30da6628923202cbf6e877405ea6d484e9eb88ac007e0fee0100000017a914fe7dfeeb1cbf6330590bc7ee2c47a2de593f192087024730440220625b6fd7299cfd14e6bdaa63cef809da54d4016c6caf5d268fc80c48d7fb41cc02200da35a319d63926112aa26952933ce590e67023993072ab10ab2bfb44f55704f012103c97015da537daded1ac5fd4b5f9cfe55d1d77aed63da77da097d2af08736133900000000",
        "blockhash": "0000000000000000000dfeca4aac6372aa5aff5beb3bd13105eedb2269375723",
        "confirmations": 103,
        "time": 1541981822,
        "blocktime": 1541981822
    },
    "error": null,
    "id": null
}
That is how it works, you need to look up the previous transaction where that output exists in order to get the value. The equivalent call using bitcoin-cli is:

$ bitcoin-cli getrawtransaction 9de8923855b2c56bc903c39418298fa8c185e5feb99cb32bfa31b9d06700ced8 2


then you can find the vout with index 1.