16(while)

#include <iostream>

using namespace std;

int main()
{
    int a,b;
    cout<<"A=";
    cin>>a;
    int c=a;
    cout<<"B=";
    cin>>b;
    if(a<=b){
        while(c<=b){
            if(c%2==0&&c<0){
                cout<<c;
            }
            c++;
        }
    }
    else{
        cout<<"error";
    }
    return 0;
}