#include <bits/stdc++.h>
using namespace std;
constexpr int N = 10000000;
pair<int, int> p[N];
/** Interface */
template<class T = int>
inline T readInt();
inline double readDouble();
inline int readUInt();
inline int readChar();
inline void readWord(char *s);
inline bool readLine(char *s); // do not save '\n'
inline bool isEof();
inline int peekChar();
inline bool seekEof();
template<class T>
inline void writeInt(T x, int len = -1);
template<class T>
inline void writeUInt(T x, int len = -1);
inline void writeChar(int x);
inline void writeWord(const char *s);
inline void writeDouble(double x, int len = 0);
inline void flush();
/** Read */
static const int buf_size = 4096;
static char buf[buf_size];
static int buf_len = 0, buf_pos = 0;
inline bool isEof() {
if (buf_pos == buf_len) {
buf_pos = 0, buf_len = fread(buf, 1, buf_size, stdin);
if (buf_pos == buf_len)
return 1;
}
return 0;
}
inline int getChar() {
return isEof() ? -1 : buf[buf_pos++];
}
inline int peekChar() {
return isEof() ? -1 : buf[buf_pos];
}
inline bool seekEof() {
int c;
while ((c = peekChar()) != -1 && c <= 32)
buf_pos++;
return c == -1;
}
inline int readChar() {
int c = getChar();
while (c != -1 && c <= 32)
c = getChar();
return c;
}
inline int readUInt() {
int c = readChar(), x = 0;
while ('0' <= c && c <= '9')
x = x * 10 + c - '0', c = getChar();
return x;
}
template<class T>
inline T readInt() {
int s = 1, c = readChar();
T x = 0;
if (c == '-')
s = -1, c = getChar();
while ('0' <= c && c <= '9')
x = x * 10 + c - '0', c = getChar();
return s == 1 ? x : -x;
}
inline double readDouble() {
int s = 1, c = readChar();
double x = 0;
if (c == '-')
s = -1, c = getChar();
while ('0' <= c && c <= '9')
x = x * 10 + c - '0', c = getChar();
if (c == '.') {
c = getChar();
double coef = 1;
while ('0' <= c && c <= '9')
x += (c - '0') * (coef *= 1e-1), c = getChar();
}
return s == 1 ? x : -x;
}
inline void readWord(char *s) {
int c = readChar();
while (c > 32)
*s++ = c, c = getChar();
*s = 0;
}
inline bool readLine(char *s) {
int c = getChar();
while (c != '\n' && c != -1)
*s++ = c, c = getChar();
*s = 0;
return c != -1;
}
/** Write */
static int write_buf_pos = 0;
static char write_buf[buf_size];
inline void writeChar(int x) {
if (write_buf_pos == buf_size)
fwrite(write_buf, 1, buf_size, stdout), write_buf_pos = 0;
write_buf[write_buf_pos++] = x;
}
inline void flush() {
if (write_buf_pos)
fwrite(write_buf, 1, write_buf_pos, stdout), write_buf_pos = 0;
}
template<class T>
inline void writeInt(T x, int output_len) {
if (x < 0)
writeChar('-'), x = -x;
char s[24];
int n = 0;
while (x || !n)
s[n++] = '0' + x % 10, x /= 10;
while (n < output_len)
s[n++] = '0';
while (n--)
writeChar(s[n]);
}
template<class T>
inline void writeUInt(T x, int output_len) {
char s[24];
int n = 0;
while (x || !n)
s[n++] = '0' + x % 10, x /= 10;
while (n < output_len)
s[n++] = '0';
while (n--)
writeChar(s[n]);
}
inline void writeWord(const char *s) {
while (*s)
writeChar(*s++);
}
inline void writeDouble(double x, int output_len) {
if (x < 0)
writeChar('-'), x = -x;
int t = (int) x;
writeUInt(t), x -= t;
writeChar('.');
for (int i = output_len - 1; i > 0; i--) {
x *= 10;
t = std::min(9, (int) x);
writeChar('0' + t), x -= t;
}
x *= 10;
t = std::min(9, (int) (x + 0.5));
writeChar('0' + t);
}
int main() {
int n;
cin >> n;
for (int i = 0; i < n; ++i) {
int a = readUInt(), b = readUInt();
p[i].first = a + b, p[i].second = b - a;
}
sort(p, p + n);
int ans = 0, mx = -1e9;
for (int i = n - 1; i >= 0; --i) {
ans += (mx < p[i].second && (mx = p[i].second, 1));
}
writeUInt(ans);
flush();
return 0;
}
