/in/foo.cc: In function 'int main()':
/in/foo.cc:7:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int i=0;i<s.size();i++){
              ~^~~~~~~~~
/in/foo.cc:8:15: warning: suggest parentheses around '&&' within '||' [-Wparentheses]
   if(s[i]>='a'&&s[i]<='z'||s[i]>='A'&&s[i]<='Z') sum++;