main=do
    getLine
    a<-getLine>>=return.map(read::String->Int).words
    let b0=head a
        a1=sum a
        a1'=sum$zipWith(*)a(cycle[1,-1])
        b1=(a1-a1')`div`2
        b2=(a1+a1')`div`2-b0
        r'=(reverse.dropWhile(==0).reverse)[b0,b1,b2]
        r=if null r' then[0]else r'
    print$length r-1
    putStrLn$(unwords.map show)r