9.2(ТАКСИ)

#include <iostream>

using namespace std;


int main() {

    int start1,start2,a1,a2,price;
    cin>>start1;
    cin>>a1;
    cin>>start2;
    cin>>a2;
    price=start1;
    while(start1<start2)
    {
        start1+=a1;
        if (start1>=start2)
        {
            price=start2;
            break;
        }

        start2-=a2;
        if (start1>=start2)
        {
            price=start1;
            break;
        }

    }
    cout<<price;


    return 0;

}