a={}for k=1,4 do for s in string.gmatch(io.read(), "[^%s]+")do a[#a+1]=s end end for z=1,9 do a[z]=a[z]-a[9+z%3]end print(math.floor(-(a[8]*(a[4]*a[3]-a[1]*a[6])+a[7]*(a[2]*a[6]-a[5]*a[3])+a[9]*(a[1]*a[5]-a[4]*a[2]))/6))