foo.cc: In function 'int main()':
foo.cc:24:14: warning: array subscript has type 'char' [-Wchar-subscripts]
   cnt[j][s[j]]++;
              ^
foo.cc:33:18: warning: suggest parentheses around comparison in operand of '&' [-Wparentheses]
    if(cnt[j][i]&1==1) sig=i;
                 ~^~~
foo.cc:36:4: warning: 'sig' may be used uninitialized in this function [-Wmaybe-uninitialized]
    if(v[i][0]==sig) {
    ^~
foo.cc:15:6: warning: 'len' may be used uninitialized in this function [-Wmaybe-uninitialized]
  int len;
      ^~~

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