foo.cc: In function ‘bool cmp()’:
foo.cc:39:16: warning: unused variable ‘j’ [-Wunused-variable]
   39 |         int i, j, t, c = 0;
      |                ^
foo.cc:39:22: warning: unused variable ‘c’ [-Wunused-variable]
   39 |         int i, j, t, c = 0;
      |                      ^
foo.cc: In function ‘void decc()’:
foo.cc:58:25: warning: comparison of integer expressions of different signedness: ‘std::vector<short int>::size_type’ {aka ‘long unsigned int’} and ‘int’ [-Wsign-compare]
   58 |         while (b.size() < t) b.insert(b.begin(), 0);
      |                ~~~~~~~~~^~~
foo.cc: In function ‘int main()’:
foo.cc:116:23: warning: comparison of integer expressions of different signedness: ‘int’ and ‘std::vector<short int>::size_type’ {aka ‘long unsigned int’} [-Wsign-compare]
  116 |         for (i = 0; i < a.size(); i++) cout << a[i];
      |                     ~~^~~~~~~~~~
foo.cc:93:16: warning: unused variable ‘j’ [-Wunused-variable]
   93 |         int i, j, k, t = 0;
      |                ^
foo.cc:93:19: warning: unused variable ‘k’ [-Wunused-variable]
   93 |         int i, j, k, t = 0;
      |                   ^
foo.cc:98:13: warning: unused variable ‘l’ [-Wunused-variable]
   98 |         int l = s.length();
      |             ^