{
  "title": "Bit Strings",
  "category": "Introductory Problems",
  "slug": "bit-strings",
  "officialUrl": "https://cses.fi/problemset/task/1617",
  "level": "basic",
  "tags": ["modular arithmetic", "pow"],
  "status": "solved",
  "order": 9,
  "summary": "Count how many binary strings of length n exist, modulo 1e9+7."
}