#include <iostream>
using namespace std;

int f(int x){
	if(x<0)return -x;
	return x;
}

int main() {
	// your code goes here
	int x,y,x1,y1,ans=0;
	std::cin>>x>>y>>x1>>y1;
	if((x==y)&&(x1==y1)&&(x1<x)){
		ans=1;
	}
	ans+=std::min(x,y)+f(x-y);
	std::cout<<ans<<"\n";
	return 0;
}