#include <bits/stdc++.h>
using namespace std;
using int64 = long long;
static const int BUFSIZE = 1 << 20;
static char buf[BUFSIZE];
static int bufpos = 0, buflen = 0;
static inline char nextChar() {
if (bufpos >= buflen) {
buflen = (int)fread(buf, 1, BUFSIZE, stdin);
bufpos = 0;
if (buflen == 0) return 0;
}
return buf[bufpos++];
}
static inline bool readUnsignedLongLong(unsigned long long &out) {
char c; out = 0;
do { c = nextChar(); if (!c) return false; } while (c <= ' ');
while (c > ' ') {
out = out * 10 + (c - '0');
c = nextChar();
if (!c) break;
}
return true;
}
int main() {
ios::sync_with_stdio(false);
cin.tie(nullptr);
unsigned long long Nu;
if (!readUnsignedLongLong(Nu)) return 0;
size_t N = (size_t)Nu;
// allocate arrays for A and B
// A = X + Y (use int64)
// B = Y - X (use int64)
int64 *A = (int64*)malloc(sizeof(int64) * N);
int64 *B = (int64*)malloc(sizeof(int64) * N);
if (!A || !B) {
fprintf(stderr, "Allocation failed\n");
return 0;
}
for (size_t i = 0; i < N; ++i) {
unsigned long long Xu, Yu;
readUnsignedLongLong(Xu);
readUnsignedLongLong(Yu);
int64 X = (int64)Xu;
int64 Y = (int64)Yu;
A[i] = X + Y; // 0 .. 2e9 fits in 64-bit
B[i] = Y - X; // -1e9 .. 1e9 fits in 64-bit
}
// compute suffix maximum of A
int64 *suffA = (int64*)malloc(sizeof(int64) * N);
if (!suffA) {
fprintf(stderr, "Allocation failed\n");
return 0;
}
suffA[N-1] = A[N-1];
for (int i = (int)N - 2; i >= 0; --i) {
suffA[i] = max(A[i], suffA[i+1]);
}
long long rods = 0;
int64 prefMinB = LLONG_MAX; // min of B[0..i-1]
for (size_t i = 0; i < N; ++i) {
bool coveredLeft = (i > 0 && prefMinB <= B[i]); // exists j < i with B[j] <= B[i]
bool coveredRight = (i + 1 < N && suffA[i+1] >= A[i]); // exists j > i with A[j] >= A[i]
if (!coveredLeft && !coveredRight) ++rods;
// update prefix min for next indices
if (B[i] < prefMinB) prefMinB = B[i];
}
printf("%lld\n", rods);
free(A);
free(B);
free(suffA);
return 0;
}
