Subpunct A

#include <iostream>
using namespace std;
int main()
{
    int x,a,r,p;
    cin>>x;
    p=1;
    r=0;
    while(x!=0)
    {
        a=x%10;
        if(a<=5)
        {
            r=r+a*p;
            p=p*10;
        }
        x=x/10;
    }
    cout<<r;
    return 0;
}