foo.cc: In function 'int main()':
foo.cc:4:9: warning: unused variable 'i' [-Wunused-variable]
    4 | int n,m,i,j,k;
      |         ^
foo.cc:5:6: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
    5 | scanf("%d,%d",&n,&m);
      | ~~~~~^~~~~~~~~~~~~~~

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