'int' object is not subscriptable (парсинг json)?

dict = {
  "response": {
  "62": {
  "type": "photo",
  "photo": {
    "src_big": "https://pp.userapi.com/xxxx.jpg"
  }
  },
  "58": {
  "type": "photo",
  "photo":  
    "src_big": "https://pp.userapi.com/yyyy.jpg"
  }
  }
  }
  }
  x = dict['response']
  sizes = [x[i]['photo'] for i in x]
  print(sizes)

File "/home/script.py", line 3623, in main
    sizes = [x[i]['photo'] for i in x]
  File "/home/script.py", line 3623, in <listcomp>
    sizes = [x[i]['photo'] for i in x]
TypeError: 'int' object is not subscriptable