/in/foo.cc: In function 'int main()':
/in/foo.cc:10:22: warning: suggest parentheses around assignment used as truth value [-Wparentheses]
  while (ch = getchar()) {
                      ^
/in/foo.cc:17:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for (int i = 0; i <= data.size();i++) {
                  ~~^~~~~~~~~~~~~~
/in/foo.cc:26:9: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   if (j == data.size()) {
       ~~^~~~~~~~~~~~~~
/in/foo.cc:38:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for (int i = 0; i <= data.size(); i++) {
                  ~~^~~~~~~~~~~~~~
/in/foo.cc:47:9: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   if (j == data.size()) {
       ~~^~~~~~~~~~~~~~