var reader = require('readline').createInterface({
    input: process.stdin,
    output: process.stdout
});

var args = [];

reader.on('line', function (input) {
  args.push(input);
});


reader.on('close', function () {
    var str = args[0].split(" ");
    var num = [];
    var count = 0;
    for(var i = 0; i < str.length; i++){
        num[i] = parseInt(str[i]);
    }
    while (num[0] % num[2] !== 0) {
        num[0]++;
        if(num[0] >= num[1]){
            break;
        }
    }
    for(num[0]; num[0] <= num[1]; num[0] += num[2]){
        count++;
    }
    console.log(count);
});
