foo.cc: In function 'int main()':
foo.cc:7:7: error: expected primary-expression before ')' token
 while()
       ^
foo.cc:10:4: error: unable to find numeric literal operator 'operator""n'
 16=3n;
    ^~
foo.cc:10:4: note: use -std=gnu++11 or -fext-numeric-literals to enable more built-in suffixes