n=int(input()) if n<2000: ans=n*0.9 print("%.1f"%ans) elif 3000>n>=2000: ans=n*0.8 print("%.1f"%ans) elif 4000>n>=3000: ans=n*0.7 print("%.1f"%ans) elif n>=4000: ans=n*0.6 print("%.1f"%ans)