foo.cc: In function 'int main()':
foo.cc:18:6: error: unable to find numeric literal operator 'operator""x'
    y=2x-1;
      ^~
foo.cc:18:6: note: use -std=gnu++11 or -fext-numeric-literals to enable more built-in suffixes
foo.cc:22:2: error: 'else' without a previous 'if'
  else
  ^~~~
foo.cc:30:2: error: 'else' without a previous 'if'
  else if(x>25)
  ^~~~
foo.cc:32:5: error: unable to find numeric literal operator 'operator""x'
   y=10x+294;
     ^~~
foo.cc:32:5: note: use -std=gnu++11 or -fext-numeric-literals to enable more built-in suffixes

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