so easy!

#include<bits/stdc++.h>
using namespace std;
char c[]={"0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ"};
string f(int a,int r){
    string s,s1="";
    while(a){
        s+=c[a%r];
        a/=r;
    }
    for(int i=s.size()-1;i>=0;i--)s1+=s[i];
    return s1;
}
int main(){
    int a,b,r;
    cin>>a>>b>>r;
    string a1=f(a,r);
    string b1=f(b,r);
    if(a1>b1)cout<<a1;
    else cout<<b1;
    return 0;
}

c++98 so easy!