foo.c: In function 'main':
foo.c:9:2: warning: 'gets' is deprecated [-Wdeprecated-declarations]
  gets(s1);gets(s2);
  ^~~~
In file included from /usr/include/stdio.h:862:0,
                 from foo.c:1:
/usr/include/x86_64-linux-gnu/bits/stdio2.h:232:1: note: declared here
 gets (char *__str)
 ^~~~
foo.c:9:2: warning: 'gets' is deprecated [-Wdeprecated-declarations]
  gets(s1);gets(s2);
  ^~~~
In file included from /usr/include/stdio.h:862:0,
                 from foo.c:1:
/usr/include/x86_64-linux-gnu/bits/stdio2.h:232:1: note: declared here
 gets (char *__str)
 ^~~~
foo.c: In function 'Concat':
foo.c:20:22: error: 'i' undeclared (first use in this function)
  for(int j=1;j<n;j++,i++)
                      ^
foo.c:20:22: note: each undeclared identifier is reported only once for each function it appears in
foo.c: In function 'main':
foo.c:9:2: warning: ignoring return value of 'gets', declared with attribute warn_unused_result [-Wunused-result]
  gets(s1);gets(s2);
  ^~~~~~~~
foo.c:9:11: warning: ignoring return value of 'gets', declared with attribute warn_unused_result [-Wunused-result]
  gets(s1);gets(s2);
           ^~~~~~~~

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