链接
https://pintia.cn/problem-sets/994805342720868352/problems/994805507225665536
题解
二分答案，需要高精度
代码
def tonum(c):
if c>='0' and c<='9':
return int(c)
return ord(c)-0x61+10
def chg(s,base):
ans=0
for i in range(len(s)):
if tonum(s[i])>=base : return -1
ans=ans*base+tonum(s[i])
return ans
n1,n2,tag,radix = input().split()
if tag=='2': n1, n2 = n2, n1
l,r = 2,1000000000000
mid = l+r>>1
n1=chg(n1,int(radix))
while l<r:
tmp = chg(n2,mid)
if tmp < n1: l=mid+1
else : r=mid
mid = l+r>>1
if chg(n2,l)==n1:
print(l)
else : print('Impossible')