SHARYGIN 2005 Problem 6

Side $AB$ of triangle $ABC$ was divided into $n$ equal parts (dividing points $B_0 = A, B_1, B_2, ..., B_n = B$ ), and side $AC$ of this triangle was divided into $(n + 1)$ equal parts (dividing points $C_0 = A, C_1, C_2, ..., C_{n+1} = C$ ). Colored are the triangles $C_iB_iC_{i+1}$ (where $i = 1,2, ..., n$ ). What part of the area of the triangle is painted over?