Hi,
I am a beginner in Prolog, i have
c-in(delhi,india).
c-in(prague,czechoslovakia).
c-in(bratislava,czechoslovakia).
c-in(berlin,germany).
c-in(leipzing,germany).
c-in(bonn,germany).
c-in(hamburg,germany).
c-in(belgrade,yugoslavia).
c-in(london,united_kingdom)...