a sequence a_1 a_2 dot a_n call good element a_i exist element a_j ne j a_ia_j power 2d nonnegative integer dFor example follow sequence good 5 3 11 example a_15 choose a_23 note sum power similarly element find a_2 a_3 1 1 1 1023 7 39 89 25 89 note definition sequence length 0 goodFor example follow sequence good 16 a_116 impossible find element a_j sum power 4 16 a_14 impossible find element a_j sum power 1 3 2 8 8 8 a_32 impossible find element a_j sum power you give sequence a_1 a_2 dot a_n what minimum number element need remove good you delete arbitrary set element