蓝桥杯-好数
#include <iostream>
using namespace std;
const int N=1e7+10;
int a[N];
int n;
bool isGoodNum(int x)
{
int count=0;
while(x>0)
{
a[++count]=x%10;
x=x/10;
}
for(int i=1;i<=count;i++)
{
if((i%2!=0)&&(a[i]%2==0)) return false;
if((i%2==0)&&(a[i]%2!=0)) return false;
}
return true;
}
int main()
{
cin>>n;
int count=0;
for(int i=1;i<=n;i++)
{
if(isGoodNum(i)){
count++;
}
}
cout<<count<<endl;
return 0;
}