{ diff(x1, t) = 0,
  diff(x2, t) = (2*k15*(k8*k17/((1 + k18/k11)*k10 + k17) + k3*k4/(10 - 9*k7)/(65*1/2)/4*k17/(k17 + 2*k6) - abs(k8*k17/((1 + k18/k11)*k10 + k17) - k3*k4/(10 - 9*k7)/(65*1/2)/4*k17/(k17 + 2*k6)))/2 + 3/2*k15*21/100*k18/k11/(k17/k10)*(k8*k17/((1 + k18/k11)*k10 + k17) + k3*k4/(10 - 9*k7)/(65*1/2)/4*k17/(k17 + 2*k6) - abs(k8*k17/((1 + k18/k11)*k10 + k17) - k3*k4/(10 - 9*k7)/(65*1/2)/4*k17/(k17 + 2*k6)))/2 + (-1)*k15*x2/k1*x3/k2*k8)/k15,
  diff(x3, t) = ((-2)*k15*(k8*k17/((1 + k18/k11)*k10 + k17) + k3*k4/(10 - 9*k7)/(65*1/2)/4*k17/(k17 + 2*k6) - abs(k8*k17/((1 + k18/k11)*k10 + k17) - k3*k4/(10 - 9*k7)/(65*1/2)/4*k17/(k17 + 2*k6)))/2 + (-2)*k15*21/100*k18/k11/(k17/k10)*(k8*k17/((1 + k18/k11)*k10 + k17) + k3*k4/(10 - 9*k7)/(65*1/2)/4*k17/(k17 + 2*k6) - abs(k8*k17/((1 + k18/k11)*k10 + k17) - k3*k4/(10 - 9*k7)/(65*1/2)/4*k17/(k17 + 2*k6)))/2 + 1*k15*k3*k4/(10 - 9*k7)/(65*1/2)/2*x6/k2)/k15,
  diff(x4, t) = 0,
  diff(x5, t) = 0 }