foo.cc:4:10: error: 'student' was not declared in this scope
 bool cmp(student a,student b){
          ^~~~~~~
foo.cc:4:10: note: suggested alternative: 'stderr'
 bool cmp(student a,student b){
          ^~~~~~~
          stderr
foo.cc:4:20: error: 'student' was not declared in this scope
 bool cmp(student a,student b){
                    ^~~~~~~
foo.cc:4:20: note: suggested alternative: 'stderr'
 bool cmp(student a,student b){
                    ^~~~~~~
                    stderr
foo.cc:4:29: error: expression list treated as compound expression in initializer [-fpermissive]
 bool cmp(student a,student b){
                             ^
foo.cc:7:16: error: expected unqualified-id before ')' token
 struct student(){
                ^
foo.cc: In function 'int main()':
foo.cc:15:10: error: elements of array 'student s [sn]' have incomplete type
  student s[sn];
          ^
foo.cc:15:10: error: storage size of 's' isn't known

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