> For two positive integer sequences $x_1,x_2,...,x_n$ and $y_1,y_2,...,y_m$ satisfying > - $x_i\neq x_j\quad \text{and}\quad y_i\neq y_j\quad \forall i,j, i \ne j$ > - $1<x_1<x_2<...<x_n<y_1<...<y_m.$ > - $x_1+x_2+...+x_n>y_1+...y_m.$ > Prove that: $x_1.x_2...x_n>y_1.y_2...y_m$. (form inernet) I don't have an ideal for this problems.Thanks for your help.