foo.c: In function 'main':
foo.c:9:2: warning: 'gets' is deprecated [-Wdeprecated-declarations]
  gets(s1);
  ^~~~
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:25:5: warning: array subscript has type 'char' [-Wchar-subscripts]
    p[s2[i]][s2[i+1]]++;
     ^
foo.c:25:12: warning: array subscript has type 'char' [-Wchar-subscripts]
    p[s2[i]][s2[i+1]]++;
            ^
foo.c:33:7: warning: array subscript has type 'char' [-Wchar-subscripts]
   if(p[s2[i]][s2[i+1]]>max)
       ^
foo.c:33:14: warning: array subscript has type 'char' [-Wchar-subscripts]
   if(p[s2[i]][s2[i+1]]>max)
              ^
foo.c:34:8: warning: array subscript has type 'char' [-Wchar-subscripts]
   max=p[s2[i]][s2[i+1]];
        ^
foo.c:34:15: warning: array subscript has type 'char' [-Wchar-subscripts]
   max=p[s2[i]][s2[i+1]];
               ^
foo.c:40:7: warning: array subscript has type 'char' [-Wchar-subscripts]
   if(p[s2[i]][s2[i+1]]==max&&flag[s2[i]][s2[i+1]]==0)
       ^
foo.c:40:14: warning: array subscript has type 'char' [-Wchar-subscripts]
   if(p[s2[i]][s2[i+1]]==max&&flag[s2[i]][s2[i+1]]==0)
              ^
foo.c:40:34: warning: array subscript has type 'char' [-Wchar-subscripts]
   if(p[s2[i]][s2[i+1]]==max&&flag[s2[i]][s2[i+1]]==0)
                                  ^
foo.c:40:41: warning: array subscript has type 'char' [-Wchar-subscripts]
   if(p[s2[i]][s2[i+1]]==max&&flag[s2[i]][s2[i+1]]==0)
                                         ^
foo.c:43:9: warning: array subscript has type 'char' [-Wchar-subscripts]
     flag[s2[i]][s2[i+1]]=1;
         ^
foo.c:43:16: warning: array subscript has type 'char' [-Wchar-subscripts]
     flag[s2[i]][s2[i+1]]=1;
                ^
foo.c:9:2: warning: ignoring return value of 'gets', declared with attribute warn_unused_result [-Wunused-result]
  gets(s1);
  ^~~~~~~~
/tmp/ccQfWWxA.o: In function `main':
foo.c:(.text.startup+0x87): warning: the `gets' function is dangerous and should not be used.

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