Language: C++

#include<bits/stdc++.h>
using namespace std;
char c[101][101];
long long a,b;
{
   long long sum=0,x=1;
   char ch=getchar();
   while (ch<'0'||ch>'9')
   {
       if (ch=='-')
	     x=-1;
	   ch=getchar();
   }
   while (ch>='0'&&ch<='9')
   {
   	   sum=sum*10+ch-'0';
	   ch=getchar();
   }
   return sum*x;
}
inline void write(long long x)
{
    if (x<0)
	{
        putchar('-');
        x=-x;
    }
    if (x>9)
      write(x/10);
    putchar(x%10+'0');
    return;
}
int main()
{
	a=read()-1;b=read()-1;
	memset(c,'.',sizeof(c));
	for (register int i=51;i<=100;++i)
	  for (register int j=1;j<=100;++j)
		c[i][j]='#';
	for (register int i=1;i<=50&&b;i+=2)
	  for (register int j=1;j<=100&&b;j+=2)
	  {
		c[i][j]='#';
		--b;
	  }
	for (register int i=100;i>50&&a;i-=2)
	  for (register int j=1;j<=100&&a;j+=2)
	  {
	  	c[i][j]='.';
		--a;
	  }
	write(100);putchar(' ');
	write(100);putchar('\n');
	for (register int i=1;i<=100;++i)
	{
		for (register int j=1;j<=100;++j)
		  putchar(c[i][j]);
		putchar('\n');
	}
	return 0;
}

Compiler output:
a.cc:5:1: error: expected unqualified-id before '{' token
    5 | {
      | ^
a.cc: In function 'int main()':
a.cc:35:15: error: too few arguments to function 'ssize_t read(int, void*, size_t)'
   35 |         a=read()-1;b=read()-1;
      |           ~~~~^~
In file included from /usr/include/x86_64-linux-gnu/bits/sigstksz.h:24,
                 from /usr/include/signal.h:328,
                 from /usr/include/c++/14/csignal:42,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:116,
                 from a.cc:1:
/usr/include/unistd.h:371:16: note: declared here
  371 | extern ssize_t read (int __fd, void *__buf, size_t __nbytes) __wur
      |                ^~~~
a.cc:35:26: error: too few arguments to function 'ssize_t read(int, void*, size_t)'
   35 |         a=read()-1;b=read()-1;
      |                      ~~~~^~
/usr/include/unistd.h:371:16: note: declared here
  371 | extern ssize_t read (int __fd, void *__buf, size_t __nbytes) __wur
      |                ^~~~
a.cc:37:27: warning: ISO C++17 does not allow 'register' storage class specifier [-Wregister]
   37 |         for (register int i=51;i<=100;++i)
      |                           ^
a.cc:38:29: warning: ISO C++17 does not allow 'register' storage class specifier [-Wregister]
   38 |           for (register int j=1;j<=100;++j)
      |                             ^
a.cc:40:27: warning: ISO C++17 does not allow 'register' storage class specifier [-Wregister]
   40 |         for (register int i=1;i<=50&&b;i+=2)
      |                           ^
a.cc:41:29: warning: ISO C++17 does not allow 'register' storage class specifier [-Wregister]
   41 |           for (register int j=1;j<=100&&b;j+=2)
      |                             ^
a.cc:46:27: warning: ISO C++17 does not allow 'register' storage class specifier [-Wregister]
   46 |         for (register int i=100;i>50&&a;i-=2)
      |                           ^
a.cc:47:29: warning: ISO C++17 does not allow 'register' storage class specifier [-Wregister]
   47 |           for (register int j=1;j<=100&&a;j+=2)
      |                             ^
a.cc:54:27: warning: ISO C++17 does not allow 'register' storage class specifier [-Wregister]
   54 |         for (register int i=1;i<=100;++i)
      |                           ^
a.cc:56:35: warning: ISO C++17 does not allow 'register' storage class specifier [-Wregister]
   56 |                 for (register int j=1;j<=100;++j)
      |                                   ^