foo.cc: In function 'bool check()':
foo.cc:8:15: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
    8 |  for(int i=0;i<=m.size()/2;i++)
      |              ~^~~~~~~~~~~~
foo.cc: In function 'int main()':
foo.cc:39:2: warning: this 'for' clause does not guard... [-Wmisleading-indentation]
   39 |  for(int i=1;i<=30;i++)
      |  ^~~
foo.cc:41:3: note: ...this statement, but the latter is misleadingly indented as if it were guarded by the 'for'
   41 |   if(check()){
      |   ^~
foo.cc:42:21: error: 'i' was not declared in this scope
   42 |    printf("STEP=%d",i);
      |                     ^
foo.cc:33:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   33 |  scanf("%d",&n);
      |  ~~~~~^~~~~~~~~

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