foo.cc:2:1: error: '::main' must return 'int'
    2 | void main(){
      | ^~~~
foo.cc: In function 'int main()':
foo.cc:4:6: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
    4 | scanf("%d%d%d",&a,&b,&c);
      | ~~~~~^~~~~~~~~~~~~~~~~~~

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