dy = (-1,0,1,0)
dx = (0,1,0,-1)
from collections import deque

def main():
    L,R,M,K = map(int,input().split())
    if R - L >= M:
        mod_min = 0
        mod_max = M - 1
    else:
        x = L%M
        y = R%M
        if y - x >= 0:
            mod_min = x
            mod_max = y
        else:
            print('Yes')
            return
    min_tot = mod_min * K
    max_tot = mod_max * K
    if max_tot // M - (min_tot - 1) // M >= 1:
        print('Yes')
    else:
        print('No')

if __name__ == '__main__':
    main()