#include iostream

int main()
{
    int x1, x2,  y1, y2;
    stdcin  x1  x2  y1  y2;
    if (x1 == y1   x2 == y2  x1 - y1  == x2 - y2  y1  -  x1 == y2 - x2   -(x1 -  y1) == x2 - y2  -(y1 - x1) == y2-x2) {
        stdcout  yes;
    }
    else{
        stdcout  no;
    }
    
}