Language: C++

import java.io.*;
import java.util.*;

public class Main {
    public static void main(String[] args) {
        FastScanner fs = new FastScanner();
        int N = fs.nextInt();
        char S[] = fs.next().toCharArray();
        char T[] = fs.next().toCharArray();
        for (int i = 0; i < N; i++) {
          System.out.print(S[i]);
          System.out.print(T[i]);
        }
    }
}

class FastScanner {
    private final InputStream in = System.in;
    private final byte[] buffer = new byte[1024];
    private int ptr = 0;
    private int buflen = 0;

    private boolean hasNextByte() {
        if (ptr < buflen) {
            return true;
        } else {
            ptr = 0;
            try {
                buflen = in.read(buffer);
            } catch (IOException e) {
                e.printStackTrace();
            }
            if (buflen <= 0) {
                return false;
            }
        }
        return true;
    }

    private int readByte() {
        if (hasNextByte())
            return buffer[ptr++];
        else
            return -1;
    }

    private static boolean isPrintableChar(int c) {
        return 33 <= c && c <= 126;
    }

    public boolean hasNext() {
        while (hasNextByte() && !isPrintableChar(buffer[ptr]))
            ptr++;
        return hasNextByte();
    }

    public String next() {
        if (!hasNext())
            throw new NoSuchElementException();
        StringBuilder sb = new StringBuilder();
        int b = readByte();
        while (isPrintableChar(b)) {
            sb.appendCodePoint(b);
            b = readByte();
        }
        return sb.toString();
    }

    public long nextLong() {
        if (!hasNext())
            throw new NoSuchElementException();
        long n = 0;
        boolean minus = false;
        int b = readByte();
        if (b == '-') {
            minus = true;
            b = readByte();
        }
        if (b < '0' || '9' < b) {
            throw new NumberFormatException();
        }
        while (true) {
            if ('0' <= b && b <= '9') {
                n *= 10;
                n += b - '0';
            } else if (b == -1 || !isPrintableChar(b)) {
                return minus ? -n : n;
            } else {
                throw new NumberFormatException();
            }
            b = readByte();
        }
    }

    public int nextInt() {
        long nl = nextLong();
        if (nl < Integer.MIN_VALUE || nl > Integer.MAX_VALUE)
            throw new NumberFormatException();
        return (int) nl;
    }

    public double nextDouble() {
        return Double.parseDouble(next());
    }
}

Compiler output:
a.cc:1:1: error: 'import' does not name a type
    1 | import java.io.*;
      | ^~~~~~
a.cc:1:1: note: C++20 'import' only available with '-fmodules-ts'
a.cc:2:1: error: 'import' does not name a type
    2 | import java.util.*;
      | ^~~~~~
a.cc:2:1: note: C++20 'import' only available with '-fmodules-ts'
a.cc:4:1: error: expected unqualified-id before 'public'
    4 | public class Main {
      | ^~~~~~
a.cc:18:12: error: expected ':' before 'final'
   18 |     private final InputStream in = System.in;
      |            ^~~~~~
      |            :
a.cc:18:13: error: 'final' does not name a type
   18 |     private final InputStream in = System.in;
      |             ^~~~~
a.cc:19:12: error: expected ':' before 'final'
   19 |     private final byte[] buffer = new byte[1024];
      |            ^~~~~~
      |            :
a.cc:19:13: error: 'final' does not name a type
   19 |     private final byte[] buffer = new byte[1024];
      |             ^~~~~
a.cc:20:12: error: expected ':' before 'int'
   20 |     private int ptr = 0;
      |            ^~~~
      |            :
a.cc:21:12: error: expected ':' before 'int'
   21 |     private int buflen = 0;
      |            ^~~~
      |            :
a.cc:23:12: error: expected ':' before 'boolean'
   23 |     private boolean hasNextByte() {
      |            ^~~~~~~~
      |            :
a.cc:23:13: error: 'boolean' does not name a type; did you mean 'bool'?
   23 |     private boolean hasNextByte() {
      |             ^~~~~~~
      |             bool
a.cc:40:12: error: expected ':' before 'int'
   40 |     private int readByte() {
      |            ^~~~
      |            :
a.cc:47:12: error: expected ':' before 'static'
   47 |     private static boolean isPrintableChar(int c) {
      |            ^~~~~~~
      |            :
a.cc:47:20: error: 'boolean' does not name a type; did you mean 'bool'?
   47 |     private static boolean isPrintableChar(int c) {
      |                    ^~~~~~~
      |                    bool
a.cc:51:11: error: expected ':' before 'boolean'
   51 |     public boolean hasNext() {
      |           ^~~~~~~~
      |           :
a.cc:51:12: error: 'boolean' does not name a type; did you mean 'bool'?
   51 |     public boolean hasNext() {
      |            ^~~~~~~
      |            bool
a.cc:57:11: error: expected ':' before 'String'
   57 |     public String next() {
      |           ^~~~~~~
      |           :
a.cc:57:12: error: 'String' does not name a type
   57 |     public String next() {
      |            ^~~~~~
a.cc:69:11: error: expected ':' before 'long'
   69 |     public long nextLong() {
      |           ^~~~~
      |           :
a.cc:95:11: error: expected ':' before 'int'
   95 |     public int nextInt() {
      |           ^~~~
      |           :
a.cc:102:11: error: expected ':' before 'double'
  102 |     public double nextDouble() {
      |           ^~~~~~~
      |           :
a.cc:105:2: error: expected ';' after class definition
  105 | }
      |  ^
      |  ;
a.cc: In member function 'int FastScanner::readByte()':
a.cc:41:13: error: 'hasNextByte' was not declared in this scope
   41 |         if (hasNextByte())
      |             ^~~~~~~~~~~
a.cc:42:20: error: 'buffer' was not declared in this scope; did you mean 'buflen'?
   42 |             return buffer[ptr++];
      |                    ^~~~~~
      |                    buflen
a.cc: In member function 'long int FastScanner::nextLong()':
a.cc:70:14: error: 'hasNext' was not declared in this scope
   70 |         if (!hasNext())
      |              ^~~~~~~
a.cc:71:23: error: expected type-specifier before 'NoSuchElementException'
   71 |             throw new NoSuchElementException();
      |                       ^~~~~~~~~~~~~~~~~~~~~~
a.cc:73:9: error: 'boolean' was not declared in this scope; did you mean 'bool'?
   73 |         boolean minus = false;
      |         ^~~~~~~
      |         bool
a.cc:76:13: error: 'minus' was not declared in this scope
   76 |             minus = true;
      |             ^~~~~
a.cc:80:23: error: expected type-specifier before 'NumberFormatException'
   80 |             throw new NumberFormatException();
      |                       ^~~~~~~~~~~~~~~~~~~~~
a.cc:86:36: error: 'isPrintableChar' was not declared in this scope
   86 |             } else if (b == -1 || !isPrintableChar(b)) {
      |                                    ^~~~~~~~~~~~~~~
a.cc:87:24: error: 'minus' was not declared in this scope
   87 |                 return minus ? -n : n;
      |                        ^~~~~
a.cc:89:27: error: expected type-specifier before 'NumberFormatException'
   89 |                 throw new NumberFormatException();
      |                           ^~~~~~~~~~~~~~~~~~~~~
a.cc: In member function 'int FastScanner::nextInt()':
a.cc:97:18: error: 'Integer' was not declared in this scope
   97 |         if (nl < Integer.MIN_VALUE || nl > Integer.MAX_VALUE)
      |                  ^~~~~~~
a.cc:98:23: error: expected type-specifier before 'NumberFormatException'
   98 |             throw new NumberFormatException();
      |                       ^~~~~~~~~~~~~~~~~~~~~
a.cc: In member function 'double FastScanner::nextDouble()':
a.cc:103:16: error: 'Double' was not declared in this scope; did you mean 'double'?
  103 |         return Double.parseDouble(next());
      |                ^~~~~~
      |                double
a.cc:103:35: error: 'next' was not declared in this scope; did you mean 'nextInt'?
  103 |         return Double.parseDouble(next());
      |                                   ^~~~
      |                                   nextInt