foo.cc: In function 'int main()':
foo.cc:30:9: error: expected ',' or ';' before 'if'
   30 |         if(a[i] == 0)
      |         ^~
foo.cc:32:9: warning: this 'if' clause does not guard... [-Wmisleading-indentation]
   32 |         if(a[i] == 2)
      |         ^~
foo.cc:34:3: note: ...this statement, but the latter is misleadingly indented as if it were guarded by the 'if'
   34 |   if(a[i] == 3)
      |   ^~
foo.cc:35:10: error: 'a3' was not declared in this scope; did you mean 'p3'?
   35 |   ans += a3[i + n / 2] - p3;
      |          ^~
      |          p3
foo.cc:26:7: warning: unused variable 'p' [-Wunused-variable]
   26 |   int p = (i == 0 ? 0 : s2[i - 1]);
      |       ^

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