A x B + C

AtCoder

IDabc179_c

Time2000ms

Memory256MB

Difficulty—

Given is a positive integer $N$. How many tuples $(A,B,C)$ of positive integers satisfy $A \times B + C = N$? ## Constraints * $2 \leq N \leq 10^6$ * All values in input are integers. ## Input Input is given from Standard Input in the following format: $N$ [samples]

Samples

Input #1

Output #1

3

There are $3$ tuples of integers that satisfy $A \times B + C = 3$: $(A, B, C) = (1, 1, 2), (1, 2, 1), (2, 1, 1)$.

Input #2

Output #2

Input #3

Output #3

13969985

API Response (JSON)

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  "problem": {
    "name": "A x B + C",
    "description": {
      "content": "Given is a positive integer $N$. How many tuples $(A,B,C)$ of positive integers satisfy $A \\times B + C = N$?",
      "description_type": "Markdown"
    },
    "platform": "AtCoder",
    "limit": {
      "time_limit": 2000,
      "memory_limit": 262144
    },
    "difficulty": "None",
    "is_remote": true,
    "is_sync": true,
    "sync_url": null,
    "sign": "abc179_c"
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  "statements": [
    {
      "statement_type": "Markdown",
      "content": "Given is a positive integer $N$. How many tuples $(A,B,C)$ of positive integers satisfy $A \\times B + C = N$?\n\n## Constraints\n\n*   $2 \\leq N \\leq 10^6$\n*   All values in input are integers.\n\n## Input\n...",
      "is_translate": false,
      "language": "English"
    }
  ]
}

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