foo.c:2:1: error: unknown type name 'using'
 using namespace std;
 ^~~~~
foo.c:2:17: error: expected '=', ',', ';', 'asm' or '__attribute__' before 'std'
 using namespace std;
                 ^~~
foo.c: In function 'main':
foo.c:8:2: error: 'cin' undeclared (first use in this function); did you mean 'main'?
  cin>>m>>n;
  ^~~
  main
foo.c:8:2: note: each undeclared identifier is reported only once for each function it appears in
foo.c:14:2: error: 'cout' undeclared (first use in this function)
  cout<<n;
  ^~~~

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