foo.cc: In function 'void output()':
foo.cc:6:22: warning: comparison of integer expressions of different signedness: 'int' and 'long long unsigned int' [-Wsign-compare]
    6 |         for(int i=1;i<=n;i++)
      |                     ~^~~
foo.cc:9:22: warning: comparison of integer expressions of different signedness: 'int' and 'long long unsigned int' [-Wsign-compare]
    9 |         for(int i=1;i<=m;i++)
      |                     ~^~~
foo.cc: In function 'int main()':
foo.cc:27:22: warning: comparison of integer expressions of different signedness: 'int' and 'long long unsigned int' [-Wsign-compare]
   27 |         for(int i=1;i<=n;i++)
      |                     ~^~~
foo.cc:28:30: warning: comparison of integer expressions of different signedness: 'int' and 'long long unsigned int' [-Wsign-compare]
   28 |                 for(int j=1;j<=m;j++)
      |                             ~^~~

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