def nontrivialgroup(g):
    if g[0] == [] or g[1] == []:
        return False
    return True

def group(xs):
    result = [[[xs[0]], []], [[], [xs[0]]]]
    for i in xs[1:]:
        newresult = []
        for r in result:
            newresult.append([r[0] + [i], r[1]])
            newresult.append([r[0], r[1] + [i]])
        result = newresult[:]
    return filter(nontrivialgroup, result)

def options(xs):
    if len(xs) == 1:
        return [(xs[0], str(xs[0]))]
    result = set()
    for g in group(xs):
        for a in options(g[0]):
            for b in options(g[1]):
                result.add((a[0] + b[0], "(" + str(a[1]) + "+" + str(b[1]) + ")"))
                result.add((a[0] - b[0], "(" + str(a[1]) + "-" + str(b[1]) + ")"))
                result.add((a[0] * b[0], "(" + str(a[1]) + "*" + str(b[1]) + ")"))
                if b[0] != 0:
                    result.add((float(a[0]) / b[0], "(" + str(a[1]) + "/" + str(b[1]) + ")"))
    return result

def f(xs):
    unduplicate = {}
    for i in list(options(xs)):
        unduplicate.update({i[0] : i[1]})
    for n, x in unduplicate.iteritems():
        if n - int(n) < 0.001:
            print str(int(n)) + " = " + x

# Example: f([3,3,7,7])