import sys
from gPy.Variables import declare_variable
from gPy.Models import FR
from gPy.Parameters import Factor
from math import exp
from gPy import Parameters

Parameters.precision = 6



values = 0,1
wcnf = open(sys.argv[1])
n = int(wcnf.readline().split()[2])
for i in range(1,n+1):
    declare_variable('x%d' % i,values)

highest = 0
wclauses = []
for line in wcnf:
    lits = line.split()
    cost = int(lits[0])
    if cost > highest:
        highest = cost
    lits = [int(i) for i in lits[1:-1]]
    wclauses.append((cost,lits))

fr = FR()
for (cost,clause) in wclauses:
    factor = Factor(
        variables = ['x%d' % abs(lit) for lit in clause],
        )
    breaking_inst = {}
    tautology = False
    for lit in clause:
        v = 'x%d' % abs(lit)
        val = int(lit<0)
        try:
            if breaking_inst[v] != val:
                tautology = True
                break
        except KeyError:
            breaking_inst[v] = val
    if tautology:
        continue
    if cost == highest:
        factor[breaking_inst] = 0
    else:
        factor[breaking_inst] = exp(float(-cost))

    fr *= factor

print fr