N=int(input()) while True: change=False S=str(N) for i in range(len(S)): if S[i]=='3': change=True T=S[:i] U=2 for j in range(len(S)-i-1): U=U*10+9 S=T+str(U) #S[i]='2' #for j in range(i+1,len(S)): #S[i]='9' break #print(S) N=int(S) if N%3==0: change=True N-=1 if change==False: print(N) break