foo.cc: In function 'int main()':
foo.cc:7:25: warning: unused variable 'k' [-Wunused-variable]
  int a[N],i,n,j,index,t,k;
                         ^
foo.cc:24:2: warning: 'index' may be used uninitialized in this function [-Wmaybe-uninitialized]
  if(index!=i)
  ^~

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