/in/foo.cc: In function 'int main()':
/in/foo.cc:9:24: warning: array subscript is above array bounds [-Warray-bounds]
  if(a[1]*a[1]==a[2]*a[3]||a[2]*a[2]==a[1]*a[3]||a[3]*a[3]==a[2]*a[1])
                     ~~~^