foo.cc: In function 'int main()':
foo.cc:6:5: error: 'cin' was not declared in this scope
     cin >> l >> m;
     ^~~
foo.cc:6:5: note: suggested alternative: 'main'
     cin >> l >> m;
     ^~~
     main
foo.cc:19:5: error: 'cout' was not declared in this scope
     cout << num;
     ^~~~

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