a=1/20+18(a+1)/20+(b+1)/20,b=(a+1)/12+10(b+1)/12+(c+1)/12,c=(b+1)/8+6(c+1)/8+(d+1)/8,d=(c+1)/6+4(d+1)/6+(e+1)/6,e=(d+1)/4+(e+1)/2+(f+1)/4,f=(e+1)/2+(f+1)/2

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