# | Time | Username | Problem | Language | Result | Execution time | Memory |
---|---|---|---|---|---|---|---|
1228098 | RiverFlow | Boat (APIO16_boat) | C++17 | 0 ms | 0 KiB |
#include <bits/stdc++.h>
#define nl "\n"
#define no "NO"
#define yes "YES"
#define fi first
#define se second
#define vec vector
#define task "main"
#define _mp make_pair
#define ii pair<int, int>
#define sz(x) (int)x.size()
#define all(x) x.begin(), x.end()
#define evoid(val) return void(std::cout << val)
#define FOR(i, a, b) for(int i = (a); i <= (b); ++i)
#define FOD(i, b, a) for(int i = (b); i >= (a); --i)
#define unq(x) sort(all(x)); x.resize(unique(all(x)) - x.begin())
using namespace std;
template<typename U, typename V> bool maxi(U &a, V b) {
if (a < b) { a = b; return 1; } return 0;
}
template<typename U, typename V> bool mini(U &a, V b) {
if (a > b) { a = b; return 1; } return 0;
}
const int N = (int)2e5 + 9;
const int mod = (int)1e9 + 7;
void prepare(); void main_code();
int main() {
ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);
if (fopen(task".inp", "r")) {
freopen(task".inp", "r", stdin);
freopen(task".out", "w", stdout);
}
const bool MULTITEST = 0; prepare();
int num_test = 1; if (MULTITEST) cin >> num_test;
while (num_test--) { main_code(); }
}
void prepare() {};
int a[N], b[N];
void main_code() {
int n; cin >> n;
FOR(i, 1, n) cin >> a[i] >> b[i];
FOR(i, 1, n) if (a[i]!=b[i]) return 0;
dp[0]=0;
FOR(i, 1, n) {
FOR(j, 0, i-1) if (a[i]>a[j]){
dp[i]=(dp[i]+dp[j])%mod;
}
}
int ans=0;
FOR(i, 1, n) ans = (ans+dp[i])%mod;
cout << ans;
}
/* Let the river flows naturally */