/in/foo.c:2:1: error: unknown type name 'using'
 using namespace std;
 ^
/in/foo.c:2:17: error: expected '=', ',', ';', 'asm' or '__attribute__' before 'std'
 using namespace std;
                 ^
/in/foo.c: In function 'main':
/in/foo.c:23:12: warning: format '%s' expects argument of type 'char *', but argument 2 has type 'char * (*)[20]' [-Wformat=]
   if(scanf("%s",&stu[i].name)){}
            ^
/in/foo.c:32:9: warning: format '%s' expects argument of type 'char *', but argument 2 has type 'char **' [-Wformat=]
  printf("%s\n",stu[max].name);
         ^