polycarp love cipher he invent cipher call RightLeftRightLeft cipher string to encrypt string ss_1s_2 dot s_n Polycarp use follow algorithm write s_1 append current word s_2 ie write s_2 right current result prepend current word s_3 ie write s_3 leave current result append current word s_4 ie write s_4 right current result prepend current word s_5 ie write s_5 leave current result position end s for example stechno process t te cte cteh ncteh ncteho so encrypt stechno nctehogiven string t result encryption string s your task decrypt ie find string s