let i = require('fs').readFileSync('/dev/stdin', 'utf8').split('\n')
let o = 0
if (i[1] < 0) o += 2
else if (i[0] != 0) o += 1
o += Math.ceil(Math.abs(i[0] / i[2]))
o += Math.ceil(Math.abs(i[1] / i[2]))
console.log(o)