foo.cc: In function 'int main()':
foo.cc:13:15: warning: comparison of integer expressions of different signedness: 'int' and 'long long unsigned int' [-Wsign-compare]
   13 |     for(i=y1;i<=y2;i++)
      |              ~^~~~
foo.cc:18:11: warning: comparison of integer expressions of different signedness: 'int' and 'long long unsigned int' [-Wsign-compare]
   18 |     for(;i<=y2;i+=4)
      |          ~^~~~

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