foo.cc: In function 'int main()':
foo.cc:8:16: error: 'i' was not declared in this scope
    8 |   for(j=1;j<=n-i;j++)
      |                ^
foo.cc:12:16: error: 'i' was not declared in this scope
   12 |   for(j=1;j<=2*i-1;j++)
      |                ^
foo.cc:16:16: error: 'i' was not declared in this scope
   16 |   for(j=1;j<=n-i;j++)
      |                ^
foo.cc:21:1: error: expected '}' at end of input
   21 | }
      | ^
foo.cc:3:11: note: to match this '{'
    3 | int main(){
      |           ^

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