Problem Statement
Takahashi is an expert of Clone Jutsu, a secret art that creates copies of his body.
On a number line, there are $N$ copies of Takahashi, numbered $1$ through $N$. The $i$-th copy is located at position $X_i$ and starts walking with velocity $V_i$ in the positive direction at time $0$.
Kenus is a master of Transformation Jutsu, and not only can he change into a person other than himself, but he can also transform another person into someone else.
Kenus can select some of the copies of Takahashi at time $0$, and transform them into copies of Aoki, another Ninja. The walking velocity of a copy does not change when it transforms. From then on, whenever a copy of Takahashi and a copy of Aoki are at the same coordinate, that copy of Takahashi transforms into a copy of Aoki.
Among the $2^N$ ways to transform some copies of Takahashi into copies of Aoki at time $0$, in how many ways will all the copies of Takahashi become copies of Aoki after a sufficiently long time? Find the count modulo $10^9+7$.
Constraints
$1 ≤ N ≤ 200000$$1 ≤ X_i,V_i ≤ 10^9(1 ≤ i ≤ N)$$X_i$and$V_i$are integers.- All
$X_i$are distinct. - All
$V_i$are distinct.
Input
The input is given from Standard Input in the following format:
N
X_1 V_1
:
X_N V_N
Output
Print the number of the ways that cause all the copies of Takahashi to turn into copies of Aoki after a sufficiently long time, modulo $10^9+7$.
样例
3
2 5
6 1
3 7
6
4
3 7
2 9
8 16
10 8
9
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