~~ 刚A的 ~~
```cpp
#include<iostream>
#include<string>
#include<stack>
#define ll long long
using namespace std;
string s;
stack<int>a;
char ch[10005];
bool isnum(char ch)
{
if(ch<='9'&&ch>='0')return 1;
return 0;
}
int main()
{
int n,m,len;
ll sum=0,u=1;
cin>>n>>s>>m;
len=s.size();
for(int i=s.size()-1;i>=0;i--)
{
char ch=s[i];
if(isnum(ch))sum+=(ch-'0')*u;
else sum+=(ch-'A'+10)*u;
u*=n;
}
int k=0,q;
while(sum!=0)
{
q=sum%m;
if(q<10)ch[++k]=q+'0';
else ch[++k]=q-10+'A';
sum/=m;
}
for(int i=k;i>=1;i--)cout<<ch[i];
cout<<'\n';
return 0;
}
```
by junjie_zhao @ 2023-08-31 14:37:37