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())
S=""
k=26
if Nu<k:
    S+=nta(Nu)
else:
    while Nu>=k:
        R=Nu%k
        S=nta(R)+S
        Nu-=R
        k*=26
    #    print (Nu//k)
    k//=26
   # print (Nu//k)
    Nu//=k
    Nu-=1
    S=nta(Nu)+S
print(S)