foo.cc: In function 'int main()':
foo.cc:9:11: warning: comparison of integer expressions of different signedness: 'int' and 'size_t' {aka 'long unsigned int'} [-Wsign-compare]
    9 |  for(i=0;i<strlen(xm);i++)
      |          ~^~~~~~~~~~~
foo.cc:7:8: warning: unused variable 'n' [-Wunused-variable]
    7 |  int i,n=0,sum=0;
      |        ^

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