foo.c: In function 'main':
foo.c:5:1: error: 'cin' undeclared (first use in this function)
    5 | cin>>n1;
      | ^~~
foo.c:5:1: note: each undeclared identifier is reported only once for each function it appears in
foo.c: At top level:
foo.c:14:1: error: expected identifier or '(' before '}' token
   14 | }
      | ^

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