foo.cc: In function 'int main()':
foo.cc:31:37: warning: iteration 34 invokes undefined behavior [-Waggressive-loop-optimizations]
   31 |                         ans+=1ll*k[i]*(k[i]-1)/2;//组合数C(x,2)
      |                                  ~~~^
foo.cc:30:31: note: within this loop
   30 |                 for(int i=1; i<=35; i++)
      |                              ~^~~~

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Found 10 testcases.
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