import sys
dna=sys.stdin.read().strip().replace(" ", "")
c= dna.count("C")
g= dna.count("G")
gc= c+g
totalbp= len(dna)
gc_content= (gc/totalbp)*100
print(gc_content)
aW1wb3J0IHN5cwoKZG5hPXN5cy5zdGRpbi5yZWFkKCkuc3RyaXAoKS5yZXBsYWNlKCIgIiwgIiIpCmM9IGRuYS5jb3VudCgiQyIpCmc9IGRuYS5jb3VudCgiRyIpCmdjPSBjK2cKdG90YWxicD0gbGVuKGRuYSkKZ2NfY29udGVudD0gKGdjL3RvdGFsYnApKjEwMApwcmludChnY19jb250ZW50KQo=