Problema2

#include <iostream>
using namespace std;
int main()
{
    int n,r=0,p=1;
    cin>>n;
    do
    {
        if(n%10==2 || n%10==3 || n%10==5 || n%10==7)
        {
            r=r+n%10*p;
            p=p*10;
        }
        n=n/10;
    }
    while(n!=0);
    cout<<r;
    return 0;
}