#include <cassert>

#include <cctype>
#include <cerrno>
#include <cfloat>
#include <ciso646>
#include <climits>
#include <clocale>
#include <cmath>
#include <csetjmp>
#include <csignal>
#include <cstdarg>
#include <cstddef>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <ctime>
#include <ccomplex>
#include <cfenv>
#include <cinttypes>
#include <cstdbool>
#include <cstdint>
#include <ctgmath>
#include <cwchar>
#include <cwctype>

// C++
#include <algorithm>
#include <bitset>
#include <complex>
#include <deque>
#include <exception>
#include <fstream>
#include <functional>
#include <iomanip>
#include <ios>
#include <iosfwd>
#include <iostream>
#include <istream>
#include <iterator>
#include <limits>
#include <list>
#include <locale>
#include <map>
#include <memory>
#include <new>
#include <numeric>
#include <ostream>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <stdexcept>
#include <streambuf>
#include <string>
#include <typeinfo>
#include <utility>
#include <valarray>
#include <vector>
#include <array>
#include <atomic>
#include <chrono>
#include <condition_variable>
#include <forward_list>
#include <future>
#include <initializer_list>
#include <mutex>
#include <random>
#include <ratio>
#include <regex>
#include <scoped_allocator>
#include <system_error>
#include <thread>
#include <tuple>
#include <typeindex>
#include <type_traits>
#include <unordered_map>
#include <unordered_set>
//#include <boost/foreach.hpp>
//#include <boost/range/algorithm.hpp>
#define rep(i,j,k) for(int i=(int)j;i<(int)k;i++)
#define ll long long
#define Sort(v) sort(all(v))
#define INF 1e9
#define LINF 1e18
#define END return 0
#define pb push_back
#define se second
#define fi first
#define pb push_back
#define all(v) (v).begin() , (v).end()
#define MP make_pair
#define MOD 1000000007LL
#define int long long
using namespace std;
int day[12]={31,28,31,30,31,30,31,31,30,31,30,31};
// int dx[]={0,1,0,-1};
// int dy[]={1,0,-1,0};
struct edge{int to,cost;};
//typedef pair<int,int> P;

bool isupper(char c){if('A'<=c&&c<='Z')return 1;return 0;}
bool islower(char c){if('a'<=c&&c<='z')return 1;return 0;}
bool isPrime(int x){if(x==1)return 0;if(x==2)return 1;if(x%2==0)return 0;for(int i=3;i*i<=x;i++)if(x%i==0)return 0;return 1;}
bool iskaibun(string s){for(int i=0;i<s.size()/2;i++)if(s[i]!=s[s.size()-i-1])return 0;return 1;}
bool isnumber(char c){return ('0'<=c&&c<='9');}
bool isalpha(char c){return (isupper(c)||islower(c));}
void printvi(vector<int> v){rep(i,0,v.size()){if(i)cout<<" ";cout<<v[i];}cout<<endl;}
void printvil(vector<int> v){rep(i,0,v.size()){cout<<v[i]<<endl;}}
void printvvi(vector<vector<int>> v){
    rep(i,0,v.size()){
        rep(j,0,v[i].size()){
            if(j)cout<<" ";
            cout<<v[i][j];
        }
        cout<<endl;
    }
}
void printvstr(vector<string> v){
    rep(i,0,v.size()){
        cout<<v[i]<<endl;
    }
}

int gcd(int a,int b){
    if(a<b)swap(a,b);
    if(b==0)return a;
    else return gcd(b,a%b);
}

struct S{
    int id,team,ac,pena;
};

string alllower(string s){
    string ret;
    rep(i,0,s.size()){
        if(isupper(s[i]))ret+=char(s[i]+'a'-'A');
        else ret+=s[i];
    }
    return ret;
}

string first_upper(string s){
    string ret;
    rep(i,0,s.size()){
        if(i==0 && islower(s[i]))ret+=char(s[i]-('a'-'A'));
        else ret+=s[i];
    }
    return ret;
}

signed main (){
    for(;;){
        string s;cin>>s;
        char cmd;cin>>cmd;
        if(cmd=='X')break;

        vector<string> words;
        string temp;
        rep(i,0,s.size()){
            if(isupper(s[i])){
                if(i!=0)words.emplace_back(temp);
                temp=s[i];
            }else if(s[i]=='_'){
                words.emplace_back(temp);
                temp="";
            }else temp+=s[i];
        }
        words.emplace_back(temp);

        if(cmd=='L'){
            rep(i,0,words.size()){
                if(i==0)cout<<alllower(words[i]);
                else cout<<first_upper(words[i]);
            }
        }else if(cmd=='U'){
            rep(i,0,words.size())cout<<first_upper(words[i]);
        }else if(cmd=='D'){
            rep(i,0,words.size()){
                if(i)cout<<"_";
                cout<<alllower(words[i]);
            }
        }
        cout<<endl;
    }




    
}
/*
*/



Measured memory_bytes: 3052