s=""
n=int(input())
a=["0","1","2","3","4","5","6","7","8","9","A","B","C","D","E","F"]
while n>=16:
    t=n%16
    s=a[t]+s
    n=n//16
s=a[n]+s
print(s)

看这里

print(hex(int(input()))[2:].upper())

s = ""
k='123456789ABCDEF'
n=int(input())   
while n!=0:
    r = n%16
    s=k[r-1]+s
    n = n//16
print(s)