IMO 1984 LL MON34
One country has n cities and every two of them are linked by a
IMO 1984 LL MON34
Origin: MON
Problem
One country has n cities and every two of them are linked by a railroad. A railway worker should travel by train exactly once through the entire railroad system (reaching each city exactly once). If it is impossible for worker to travel by train between two cities, he can travel by plane. What is the minimal number of flights that the worker will have to use?