def nta(N): if N==0: a="A" elif N==1: a="B" elif N==2: a="C" elif N==3: a="D" elif N==4: a="E" elif N==5: a="F" elif N==6: a="G" elif N==7: a="H" elif N==8: a="I" elif N==9: a="J" elif N==10: a="K" elif N==11: a="L" elif N==12: a="M" elif N==13: a="N" elif N==14: a="O" elif N==15: a="P" elif N==16: a="Q" elif N==17: a="R" elif N==18: a="S" elif N==19: a="T" elif N==20: a="U" elif N==21: a="V" elif N==22: a="W" elif N==23: a="X" elif N==24: a="Y" elif N==25: a="Z" return a Nu=int(input()) R=Nu%26 S="" S+=nta(R) Nu-=R Nu//=26 f=0 if Nu==1: f=1 while Nu>1 or f==1: f=0 R=Nu%26 Nu-=R if R==0: R=25 else: R-=1 S=nta(R)+S Nu//=26 print(S)