#include<stdio.h>

int main(){
  long long A,B,N,M;
  scanf("%lld%lld%lld%lld",&A,&B,&N,&M);
  if(A>B){
    printf("%lld\n",B+(A-B)/(N+1));
  }
  else{
    printf("%lld\n",A+(B-A)/(M+1));
  }
}