theList = [2, 3, 5, 7]
x = 5

i = 0
while i < len(theList):
    if theList[i] == x:
        print "yes"
        break
    i = i + 1

lo = 0
hi = len(theList)
while lo < hi:
    mid = (lo + hi)/2
    if theList[mid] == x:
        print "yes"
        break
    if theList[mid] < x:
        lo = mid + 1
    else:
        hi = mid