No.1849 Three Times Value
レベル :
/ AI推定難易度 : 220
/ 実行時間制限 : 1ケース 2.000秒 / メモリ制限
: 512 MB / 標準ジャッジ問題
タグ : / 解いたユーザー数 104
作問者 :
matcharate12
/ テスター :
Shirotsume
タグ : / 解いたユーザー数 104
作問者 :
matcharate12
/ テスター :
Shirotsume
問題文最終更新日: 2022-04-01 11:33:15
English (AI translation)
This statement was translated by AI (claude-opus-5-5, effort medium) and may contain errors or differ in nuance from the original. The original statement takes precedence.
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Problem Statement
A number formed by concatenating $3$ copies of the same number as a string, such as $111,141414$, is defined as a triple number. However, a number whose most significant digit is $0$, such as $000,010101$, is not a triple number.
How many triple numbers are there among the numbers between $1$ and $N$, inclusive?
Input
$N$
・$1\le N\le 10^{15}$
Output
Output the answer.
Sample
Sample 1
Input
400
Output
3
$111,222,333$ satisfy the condition, so the answer is $3$ numbers. Therefore, output $3$.
Sample 2
Input
12
Output
0
No number satisfies the condition.
Sample 3
Input
77777777777
Output
999
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