/in/foo.c: In function 'main':
/in/foo.c:19:2: warning: suggest parentheses around assignment used as truth value [-Wparentheses]
  while(s1[j]=getchar()!='\n')
  ^~~~~
/in/foo.c:22:2: warning: 'gets' is deprecated [-Wdeprecated-declarations]
  gets(s1);
  ^~~~
In file included from /in/foo.c:1:0:
/usr/include/stdio.h:640:14: note: declared here
 extern char *gets (char *__s) __wur __attribute_deprecated__;
              ^~~~
/in/foo.c:23:2: warning: 'gets' is deprecated [-Wdeprecated-declarations]
  gets(s2);
  ^~~~
In file included from /in/foo.c:1:0:
/usr/include/stdio.h:640:14: note: declared here
 extern char *gets (char *__s) __wur __attribute_deprecated__;
              ^~~~
/in/foo.c:24:13: error: subscripted value is neither array nor pointer nor vector
  s1=Concat(s[9999],int n);
             ^
/in/foo.c:24:20: error: expected expression before 'int'
  s1=Concat(s[9999],int n);
                    ^~~
/in/foo.c:16:12: warning: variable 's' set but not used [-Wunused-but-set-variable]
  int j,i,m,s;
            ^
/in/foo.c:16:10: warning: unused variable 'm' [-Wunused-variable]
  int j,i,m,s;
          ^
/in/foo.c:16:8: warning: unused variable 'i' [-Wunused-variable]
  int j,i,m,s;
        ^