import math

i = 0
while( i<3 ) :
    print "x: "
    x = float(raw_input())
    print "y: "
    y = float(raw_input())

    # condition 1
    if( x != 0 and (abs(x) > abs(y)) ) :
        z = math.sin((x+y) / y)
        print "z = sin((x+y) / y) = " + str(z)
    # condition 2
    elif( x != 0 and (abs(x) <= abs(y)) ) :
        z = math.arccos(x / y)
        print "z = arccos(x / y) = " + str(z)
    # condition 3
    else :
        print "z = pi = " + str(math.pi)

    i = i+1