{ diff(x1, t) = ((-1)*k16*k2*x5*x1/k1/(1 + x1*(k1 + k5)/(k1*k5) + x2/k3 + x3/k7) + (-1)*k16*k6*x5*x1/k5/(1 + x1*(k1 + k5)/(k1*k5) + x2/k3 + x3/k7) + 1*k16*k12*x6*x3/k11/(1 + x4/k9 + x3/k11 + x2/k13 + x1/k15) + 1*k16*k14*x6*x2/k13/(1 + x4/k9 + x3/k11 + x2/k13 + x1/k15))/k16,
  diff(x2, t) = (1*k16*k2*x5*x1/k1/(1 + x1*(k1 + k5)/(k1*k5) + x2/k3 + x3/k7) + (-1)*k16*k4*x5*x2/k3/(1 + x1*(k1 + k5)/(k1*k5) + x2/k3 + x3/k7) + (-1)*k16*k14*x6*x2/k13/(1 + x4/k9 + x3/k11 + x2/k13 + x1/k15))/k16,
  diff(x3, t) = (1*k16*k6*x5*x1/k5/(1 + x1*(k1 + k5)/(k1*k5) + x2/k3 + x3/k7) + (-1)*k16*k8*x5*x3/k7/(1 + x1*(k1 + k5)/(k1*k5) + x2/k3 + x3/k7) + 1*k16*k10*x6*x4/k9/(1 + x4/k9 + x3/k11 + x2/k13 + x1/k15) + (-1)*k16*k12*x6*x3/k11/(1 + x4/k9 + x3/k11 + x2/k13 + x1/k15))/k16,
  diff(x4, t) = (1*k16*k4*x5*x2/k3/(1 + x1*(k1 + k5)/(k1*k5) + x2/k3 + x3/k7) + 1*k16*k8*x5*x3/k7/(1 + x1*(k1 + k5)/(k1*k5) + x2/k3 + x3/k7) + (-1)*k16*k10*x6*x4/k9/(1 + x4/k9 + x3/k11 + x2/k13 + x1/k15))/k16,
  diff(x5, t) = 0/k16,
  diff(x6, t) = 0/k16 }