Language: Java

#include <bits/stdc++.h>
using namespace std;
/*#include <ext/pb_ds/assoc_container.hpp> 
#include <ext/pb_ds/tree_policy.hpp> 
Apparently, the tree supports the same operations as the set 
(at least I haven't any problems with them before), but also there are two new features — 
find_by_order() — The first returns an iterator to the k-th largest element (counting from zero)
order_of_key() — the number of items in a set that are strictly smaller than our item. 
https://codeforces.com/blog/entry/11080
using namespace __gnu_pbds; */
using namespace std;
#define test() int t;cin>>t;for(int test=1;test<=t;test++)
#define int long long
#define MOD 1000000007
#define pb push_back 
#define ins insert
#define fast(); ios_base::sync_with_stdio(false); cin.tie(0); cout.tie(0);
#define ld long double
#define endl '\n'
int m(int a) {
    return ((a%MOD)+MOD)%MOD;
}
int p(int a, int b) {
    int res = 1;
    while(b > 0){
        if(b&1) res = m(m(res)*m(a));
        a = m(m(a)*m(a));
        b >>= 1;
    }
    return res;
}
signed main(){
    fast();
    char c;
    cin >> c;
    if(c >= 'a' && c <= 'z')    cout << 'a' << endl;
    else cout << 'A' << endl;
    cerr << "\nTime elapsed : " << 1000 * clock() / CLOCKS_PER_SEC << " ms\n";
}

Compiler output:
Main.java:1: error: illegal character: '#'
#include <bits/stdc++.h>
^
Main.java:1: error: class, interface, enum, or record expected
#include <bits/stdc++.h>
         ^
Main.java:11: error: class, interface, enum, or record expected
using namespace std;
^
Main.java:12: error: illegal character: '#'
#define test() int t;cin>>t;for(int test=1;test<=t;test++)
^
Main.java:12: error: class, interface, enum, or record expected
#define test() int t;cin>>t;for(int test=1;test<=t;test++)
        ^
Main.java:12: error: class, interface, enum, or record expected
#define test() int t;cin>>t;for(int test=1;test<=t;test++)
                     ^
Main.java:12: error: class, interface, enum, or record expected
#define test() int t;cin>>t;for(int test=1;test<=t;test++)
                            ^
Main.java:12: error: class, interface, enum, or record expected
#define test() int t;cin>>t;for(int test=1;test<=t;test++)
                                           ^
Main.java:12: error: class, interface, enum, or record expected
#define test() int t;cin>>t;for(int test=1;test<=t;test++)
                                                   ^
Main.java:13: error: illegal character: '#'
#define int long long
^
Main.java:14: error: illegal character: '#'
#define MOD 1000000007
^
Main.java:15: error: illegal character: '#'
#define pb push_back 
^
Main.java:16: error: illegal character: '#'
#define ins insert
^
Main.java:17: error: illegal character: '#'
#define fast(); ios_base::sync_with_stdio(false); cin.tie(0); cout.tie(0);
^
Main.java:17: error: class, interface, enum, or record expected
#define fast(); ios_base::sync_with_stdio(false); cin.tie(0); cout.tie(0);
                ^
Main.java:17: error: class, interface, enum, or record expected
#define fast(); ios_base::sync_with_stdio(false); cin.tie(0); cout.tie(0);
                                                  ^
Main.java:17: error: class, interface, enum, or record expected
#define fast(); ios_base::sync_with_stdio(false); cin.tie(0); cout.tie(0);
                                                              ^
Main.java:18: error: illegal character: '#'
#define ld long double
^
Main.java:18: error: class, interface, enum, or record expected
#define ld long double
        ^
Main.java:19: error: illegal character: '#'
#define endl '\n'
^
Main.java:22: error: class, interface, enum, or record expected
}
^
Main.java:25: error: class, interface, enum, or record expected
    while(b > 0){
    ^
Main.java:27: error: class, interface, enum, or record expected
        a = m(m(a)*m(a));
        ^
Main.java:28: error: class, interface, enum, or record expected
        b >>= 1;
        ^
Main.java:29: error: class, interface, enum, or record expected
    }
    ^
Main.java:31: error: class, interface, enum, or record expected
}
^
Main.java:34: error: unnamed classes are a preview feature and are disabled by default.
    char c;
    ^
  (use --enable-preview to enable unnamed classes)
Main.java:35: error: class, interface, enum, or record expected
    cin >> c;
    ^
Main.java:36: error: class, interface, enum, or record expected
    if(c >= 'a' && c <= 'z')    cout << 'a' << endl;
    ^
Main.java:37: error: class, interface, enum, or record expected
    else cout << 'A' << endl;
    ^
Main.java:38: error: class, interface, enum, or record expected
    cerr << "\nTime elapsed : " << 1000 * clock() / CLOCKS_PER_SEC << " ms\n";
    ^
Main.java:39: error: class, interface, enum, or record expected
}
^
32 errors