/in/foo.cc: In function 'int main()':
/in/foo.cc:41:18: warning: comparison of integer expressions of different signedness: 'int' and 'size_t' {aka 'long unsigned int'} [-Wsign-compare]
   41 |     for(int i=M;i<t2;++i)
      |                 ~^~~
/in/foo.cc:49:18: warning: comparison of integer expressions of different signedness: 'int' and 'size_t' {aka 'long unsigned int'} [-Wsign-compare]
   49 |     for(int i=M;i<t1;++i)
      |                 ~^~~