foo.cc:5:12: error: expected initializer before '+' token
    5 | const int N+3e5+10;
      |            ^
foo.cc:7:7: error: 'N' was not declared in this scope
    7 | PII a[N];
      |       ^
foo.cc: In function 'int main()':
foo.cc:15:22: error: 'a' was not declared in this scope
   15 |                 cin>>a[i].first>>a[i].second;
      |                      ^
foo.cc:18:14: error: 'a' was not declared in this scope
   18 |         sort(a,a+n);
      |              ^

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