4
10 4
15 1
19 3
20 1
 2
1 999999999
1000000000 1000000000
 67
1 1
3 8
4 10
7 8
9 2
10 1
11 5
12 8
13 4
16 6
18 3
19 3
22 5
24 6
27 5
28 3
29 3
30 5
32 5
33 10
34 7
35 8
36 5
41 3
42 2
43 5
46 4
48 4
49 9
52 4
53 9
55 1
56 4
59 7
68 7
69 4
71 9
72 10
74 5
76 4
77 9
80 7
81 9
82 5
83 5
84 9
85 7
86 9
87 4
88 7
89 10
90 3
91 5
92 10
93 5
94 8
95 4
96 2
97 10
98 1
99 3
100 1
101 5
102 4
103 8
104 8
105 8
 10
999999900 1000000000
999999901 1000000000
999999902 1000000000
999999903 1000000000
999999904 1000000000
999999905 1000000000
999999906 1000000000
999999907 1000000000
999999908 1000000000
999999909 1000000000
 35
1 7
3 11
6 12
7 6
8 5
9 11
15 3
16 10
22 2
23 3
25 7
27 3
34 5
35 10
37 3
39 4
40 5
41 1
44 1
47 7
48 11
50 6
52 5
57 2
58 7
60 4
62 1
67 3
68 12
69 8
70 1
71 5
72 5
73 6
74 4
 1
1000000000 1000000000
 2
100000000 1000000000
1000000000 1000000000
 10
7 12
10 2
12 2
15 1
19 2
20 1
53 25
63 10
75 12
87 1
 3
1 1
1000 1000
1000000000 1000000000
 40
1 1
2 1
3 1
4 1
5 1
6 1
7 1
8 1
9 1
10 1
11 1
12 1
13 1
14 1
15 1
16 1
17 1
18 1
19 1
20 1
21 1
22 1
23 1
24 1
25 1
26 1
27 1
28 1
29 1
30 1
31 1
32 1
33 1
34 1
35 1
36 1
37 1
38 1
39 1
40 1

4
 2
 5
 2
 10
 1
 2
 9
 3
 2

var n = +readline();

const FALL = {
    yes: {},
    maybe: {},
    no: {}
};

var fallType = function (fallTree, blockTree) {
    var distance = Math.abs(fallTree.x - blockTree.x);

    if (fallTree.h + blockTree.h < distance) {
        return FALL.yes;
    }

    if (fallTree.h < distance) {
        return blockTree.h >= distance ? FALL.yes : FALL.maybe;
    }

    return FALL.no;
};

var Tree = function (data) {
    this.x = +data[0];
    this.h = +data[1];
};

Tree.prototype.calculate = function (leftTree, rightTree) {
    this.left = fallType(this, leftTree);
    this.right = fallType(this, rightTree);
};

Tree.prototype.canFall = function () {
    return this.left === FALL.yes || this.right === FALL.yes;
};

Tree.prototype.cantFall = function () {
    return this.left === FALL.no && this.right === FALL.no;
};

var trees = [new Tree([-Infinity, 0])];
for (var i = 0; i < n; ++i) {
    trees.push(new Tree(readline().split(' ')));
}
trees.push(new Tree([+Infinity, 0]));

for (var i = 1; i <= n; ++i) {
    trees[i].calculate(trees[i - 1], trees[i + 1]);
}

var result = 0;
var state = 0;

for (var i = 1; i <= n; ++i) {
    switch (state) {
        case 0:
            if (trees[i].canFall()) {
                ++result;
                state = 0;
            } else {
                if (trees[i].cantFall()) {
                    state = 0;
                } else {
                    if (trees[i].left === FALL.no) {
                        ++result;
                        state = 1;
                    } else {
                        ++result;
                    }
                }
            }
            break;
        case 1:
            if (trees[i].canFall()) {
                ++result;
                state = 0;
            } else {
                if (trees[i].cantFall()) {
                    state = 0;
                } else {
                    if (trees[i].right === FALL.no) {
                        state = 0;
                    } else {
                        ++result;
                    }
                }
            }
            break;
    }
}

write(result);