SGU 105 Div 3

105. Div 3

time limit per test: 0.5 sec. memory limit per test: 4096 KB

There is sequence 1, 12, 123, 1234, ..., 12345678910, ... . Given first N elements of that sequence. You must determine amount of numbers in it that are divisible by 3.

Input

Input contains N (1<=N<=2³¹ - 1).

Output

Write answer to the output.

Sample Input

Sample Output

 1 #pragma comment(linker, "/STACK:1024000000,1024000000")
 2 #include <map>
 3 #include <queue>
 4 #include <vector>
 5 #include <string>
 6 #include <cmath>
 7 #include <cstdio>
 8 #include <cstring>
 9 #include <cstdlib>
10 #include <iostream>
11 #include <algorithm>
12 using namespace std;
13 #define maxn 105
14 #define ll long long
15 #define INF 0x7fffffff
16 #define eps 1e-8
17 int m,ma=-INF;
18 ll n;
19 int main(){
20     while(~scanf("%I64d", &n)){
21         printf("%I64d", n * 2 / 3);
22     }
23     return 0;
24 }

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posted @ 2013-10-31 18:59 HaibaraAi 阅读(93) 评论(0) 收藏举报

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