#include <bits/stdc++.h>

using namespace std;

int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  int tt = 1;
  //cin >> tt;
  while(tt--) {
    int x, y;
    cin >> x >> y;
    int a=min(x, y);
    int b = max(x, y);
    if(a+3 > b) {
      cout << "Yes\n";
    } else {
      cout << "No\n";
    }
  }
  return 0;
}

/*
ID: jerrywcy
LINK:
TITLE: 
LANG: C++
STATUS:
*/
#include <bits/stdc++.h>
#define DEBUG

#define init(array,x) memset(array,x,sizeof(array))

using namespace std;

typedef long long ll;

const int inf=0x3f3f3f3f;

ll sx,sy,gx,gy;
double ans;

int read(){
    int f=1,x=0;
    char ss=getchar();
    while(ss<'0'||ss>'9'){if(ss=='-')f=-1;ss=getchar();}
    while(ss>='0'&&ss<='9'){x=x*10+ss-'0';ss=getchar();}
    return f*x;
}

int main()
{
    sx=read();sy=read();gx=read();gy=read();
    if (sx>gx){swap(sx,gx);swap(sy,gy);}
    ans=sx+double(gx-sx)*sy/(gy+sy);
    printf("%.8lf\n",ans);

    return 0;
}