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545C.cpp
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545C.cpp
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#include<bits/stdc++.h>
using namespace std;
#define ll long long int
int main()
{
ll n;
cin >> n;
ll a[n][2];
for(int i =0 ; i < n ; i ++)
cin >> a[i][0] >> a[i][1];
ll dp[n][3];
memset(dp, 0 , sizeof(dp));
dp[0][0] = 0;
dp[0][1] = 1;
if( n == 1 || (a[0][0] + a[0][1] < a[1][0]) )
dp[0][2] = 1;
else
dp[0][2] = 0;
for(int i = 1 ; i < n ; i ++)
{
dp[i][0] = max(dp[i - 1][0] , max(dp[i - 1][1] , dp[i - 1][2]));
dp[i][2] = max(dp[i - 1][0] , max(dp[i - 1][1] , dp[i - 1][2]));
if( (a[i][0] - a[i][1] > a[i - 1][0]) )
dp[i][1] = 1 + max(dp[i - 1][0] , dp[i - 1][1]);
else
dp[i][1] = max(dp[i - 1][0] , dp[i - 1][1]);
if( (a[i][0] - a[i][1] > a[i - 1][0] + a[i - 1][1]))
dp[i][1] = max(dp[i][1] , 1 + dp[i - 1][2]);
if( i + 1 == n || (a[i][0] + a[i][1] < a[i + 1][0]) )
dp[i][2] += 1;
}
cout << max(dp[n - 1][0] , max(dp[n - 1][1] , dp[n - 1][2])) << endl;
}