foo.cc:3:33: error: unable to find numeric literal operator 'operator""a5'
    3 | int n,m,k,a[1605][1205],b[1605][120a5];
      |                                 ^~~~~
foo.cc:3:33: note: use '-fext-numeric-literals' to enable more built-in suffixes
foo.cc: In function 'void shun()':
foo.cc:9:25: error: 'b' was not declared in this scope
    9 |                         b[j][n+1-i]=a[i][j];
      |                         ^
foo.cc:11:18: error: 'b' was not declared in this scope
   11 |         memcpy(a,b,sizeof b);
      |                  ^
foo.cc: In function 'void chui_zhi()':
foo.cc:17:25: error: 'b' was not declared in this scope
   17 |                         b[n+1-i][j]=a[i][j];
      |                         ^
foo.cc:18:18: error: 'b' was not declared in this scope
   18 |         memcpy(a,b,sizeof b);
      |                  ^

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