#include <iostream>

int main()
{
    int N, M, P, Q;
    std::cin >> N >> M >> P >> Q;
    int now = 0;
    int blow = 0;
    
    while(N > 0)
    {
        now++;
        N-=M;
        if((now % 12) + 1 == P)
        {
            blow = Q; 
        }
        if(blow > 0)
        {
            blow--;
            N-=M;
        }
    }
    
    std::cout << now << std::endl;
    
    return 0;
}