/in/foo.c: In function 'main':
/in/foo.c:7:8: warning: multi-character character constant [-Wmultichar]
  scanf('%s%s',a,b);
        ^~~~~~
/in/foo.c:7:8: warning: passing argument 1 of 'scanf' makes pointer from integer without a cast [-Wint-conversion]
In file included from /usr/include/features.h:364:0,
                 from /usr/include/stdio.h:27,
                 from /in/foo.c:1:
/usr/include/stdio.h:448:12: note: expected 'const char * restrict' but argument is of type 'int'
 extern int __REDIRECT (scanf, (const char *__restrict __format, ...),
            ^
/in/foo.c:8:8: warning: implicit declaration of function 'strlen' [-Wimplicit-function-declaration]
  int n=strlen(a),m=strlen(b);
        ^~~~~~
/in/foo.c:8:8: warning: incompatible implicit declaration of built-in function 'strlen'
/in/foo.c:8:8: note: include '<string.h>' or provide a declaration of 'strlen'
/in/foo.c:14:7: error: 'i' undeclared (first use in this function)
  for( i=0;i<m;i++)
       ^
/in/foo.c:14:7: note: each undeclared identifier is reported only once for each function it appears in
/in/foo.c:16:11: error: 'j' undeclared (first use in this function)
   number2[j]=b[j]-'0';
           ^
/in/foo.c:34:2: warning: implicit declaration of function 'print' [-Wimplicit-function-declaration]
  print('%d',c[i]);
  ^~~~~
/in/foo.c:34:8: warning: multi-character character constant [-Wmultichar]
  print('%d',c[i]);
        ^~~~
/in/foo.c:18:6: warning: variable 'c' set but not used [-Wunused-but-set-variable]
  int c[20000],j;
      ^
/in/foo.c:9:6: warning: variable 'number1' set but not used [-Wunused-but-set-variable]
  int number1[n],number2[m];
      ^~~~~~~