A semi-annual government bond selling for R975, with a coupon of 10.3% has a YTM of 9.1%. The bond matures in 12 years, but can be called in 6 years at a call price of R1070. What value do you need to input into your calculator for "N" to calculate Yield to Call? Provide your answer, in years, as a whole number (no decimal places needed).