IDA Decompiler: How to configure Ida to correctly show "array elements left shifting proccess" when index is zero?

Question

I have a buffer in disassembly that its elements are shifted to left (apparently with controlling the zero index), the original code is:

flag = 0;
for ( i = 0; i < 10; i++ )
{
  if ( flag )
    buff[i - 1] = buff[i];
  if ( buff[i] == 4700 )
    flag = 1;
}

But IDA decompiles it as:

flag = 0;
for ( i = 0; i < cntr; i++ )
{
  if ( flag )
    *(&the_adr_just_before_buff + i) = buff[i];
  if ( buff[i] == 4700)
    flag = 1;
}

How can I solve this issue on IDA?