Maximum Sum of Digits（CodeForces 1060B）

Description

You are given a positive integer nn.

Let S(x) be sum of digits in base 10 representation of xx, for example, S(123)=1+2+3=6, S(0)=0.

Your task is to find two integers a,ba,b, such that 0≤a,b≤n, a+b=n and S(a)+S(b) is the largest possible among all such pairs.

Input

The only line of input contains an integer nn (1≤n≤1012).

Output

Print largest S(a)+S(b) among all pairs of integers a,ba,b, such that 0≤a,b≤n and a+b=n.

Sample Input

Input

35

Output

17

Input

10000000000

Output

91

Hint

In the first example, you can choose, for example, a=17 and b=18, so that S(17)+S(18)=1+7+1+8=17. It can be shown that it is impossible to get a larger answer.

In the second test example, you can choose, for example, a=5000000001 and b=4999999999, with S(5000000001)+S(4999999999)=91. It can be shown that it is impossible to get a larger answer.

相信不少人wa是这个代码

 #include<iostream>
 #include<cstdio>
 #include<cstdlib>
 #include<cstring>
 #include<string>
 #include<cmath>
 #include<map>
 #include<stack>
 #include<vector>
 #include<queue>
 #include<set>
 #include<algorithm>
 #define max(a,b)   (a>b?a:b)
 #define min(a,b)   (a<b?a:b)
 #define swap(a,b)  (a=a+b,b=a-b,a=a-b)
 #define maxn 320007
 #define N 100000000
 #define INF 0x3f3f3f3f
 #define mod 1000000009
 #define e  2.718281828459045
 #define eps 1.0e18
 #define PI acos(-1)
 #define lowbit(x) (x&(-x))
 #define read(x) scanf("%d",&x)
 #define put(x) printf("%d\n",x)
 #define memset(x,y) memset(x,y,sizeof(x))
 #define Debug(x) cout<<x<<" "<<endl
 #define lson i << 1,l,m
 #define rson i << 1 | 1,m + 1,r
 #define ll long long
 //std::ios::sync_with_stdio(false);
 //cin.tie(NULL);
 using namespace std;

 int main()
 {
     ll n,a,b;
     cin>>n;
     ll m=n,k=;
     while(m>=k)
     {
         k=k*+;
     }
     k/=;
     //cout<<k<<endl;
     a=k;
     b=n-k;
     ll sum=;
     while(a)
     {
         sum+=a%;
         a/=;
     }
     while(b)
     {
         sum+=b%;
         b/=;
     }
     cout<<sum<<endl;
     return ;
 }

你们可以尝试一下123这个样例，输出为15,但正确答案为24（99+24）。

AC代码如下：

 #include<iostream>
 #include<cstdio>
 #include<cstdlib>
 #include<cstring>
 #include<string>
 #include<cmath>
 #include<map>
 #include<stack>
 #include<vector>
 #include<queue>
 #include<set>
 #include<algorithm>
 #define max(a,b)   (a>b?a:b)
 #define min(a,b)   (a<b?a:b)
 #define swap(a,b)  (a=a+b,b=a-b,a=a-b)
 #define maxn 320007
 #define N 100000000
 #define INF 0x3f3f3f3f
 #define mod 1000000009
 #define e  2.718281828459045
 #define eps 1.0e18
 #define PI acos(-1)
 #define lowbit(x) (x&(-x))
 #define read(x) scanf("%d",&x)
 #define put(x) printf("%d\n",x)
 #define memset(x,y) memset(x,y,sizeof(x))
 #define Debug(x) cout<<x<<" "<<endl
 #define lson i << 1,l,m
 #define rson i << 1 | 1,m + 1,r
 #define ll long long
 //std::ios::sync_with_stdio(false);
 //cin.tie(NULL);
 using namespace std;

 int main()
 {
     ll n,a,b;
     cin>>n;
     ll m=n,k=;
     while(m>=k)
     {
         k=k*+;
     }
     k/=;
     //cout<<k<<endl;
     a=k;
     b=n-k;
     ll sum=;
     while(a)
     {
         sum+=a%;
         a/=;
     }
     while(b)
     {
         sum+=b%;
         b/=;
     }
     cout<<sum<<endl;
     return ;
 }