foo.cc: In function 'int main()':
foo.cc:9:23: error: invalid types 'int[int]' for array subscript
    9 |                 cin>>a[i];
      |                       ^
foo.cc:10:17: error: unable to find numeric literal operator 'operator""\U0000ff1b'
   10 |         cout<<a-1；
      |                 ^~~
foo.cc:10:17: note: use '-fext-numeric-literals' to enable more built-in suffixes
foo.cc:7:13: warning: unused variable 'b' [-Wunused-variable]
    7 |         int b[a];
      |             ^

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