On a board there are
nails, each two connected by a rope. Each rope is colored in one of
given distinct colors. For each three distinct colors, there exist three nails connected with ropes of these three colors.
a) Can
be
?
b) Can
be
?
%V0
On a board there are $n$ nails, each two connected by a rope. Each rope is colored in one of $n$ given distinct colors. For each three distinct colors, there exist three nails connected with ropes of these three colors.
a) Can $n$ be $6$ ?
b) Can $n$ be $7$ ?
Školjka 
