ps-intermediario-s53-p1.cpp

#include <bits/stdc++.h>

using namespace std;

const int maxn = 1e5+10, mod = 1e9+7;

int n, m, bit[maxn], quantidade[maxn];

struct point{
	int x, y;
	bool operator<(const point& o) const{
		if(x != o.x) return x < o.x;
		return y < o.y;
	}	
} p[maxn];

void add(int i, int v){

	while(i)
	{
		bit[i] = (bit[i]%mod + v)%mod;
		i-=(i&-i);
	}
}

int sum(int i)
{
	int soma = 0;

	for(; i <= m ; i += (i&-i))
	{
		soma = (soma%mod +bit[i])%mod;
	}
	return soma;
}

int main()
{
	cin >> n;

	for(int i = 1 ; i <= n ; ++i)
	{
		cin >> p[i].x >> p[i].y;
		m = max(m, p[i].y);
	}

	sort(p + 1, p + n + 1);
    
	int resp = 0;
	
	for(int i = 1 ; i <= n ; ++i)
	{
		quantidade[i] = (sum(p[i].y + 1)%mod + 1)%mod;
		add(p[i].y, quantidade[i]);
		resp = (resp%mod + quantidade[i])%mod;
	}
  
	cout << resp << "\n";
	
	return 0;
}