/in/foo.cc: In function 'int main()':
/in/foo.cc:8:17: warning: comparison of integer expressions of different signedness: 'int' and 'size_t' {aka 'long unsigned int'} [-Wsign-compare]
    8 |   for(int i=0; i<strlen(a); i++)
      |                ~^~~~~~~~~~
/in/foo.cc:5:7: warning: unused variable 'ch' [-Wunused-variable]
    5 |  char ch,a[100000];
      |       ^~