#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
const int N=3e5+100;

ll mod=1e9+7;
int n;
ll C[N],inv[N],a[N],b[N],ans,num[N],cnt,g[N],f[N];
int main() {
    cin>>n;
    inv[1]=1;
    for(int i=2;i<=n;i++) inv[i]=(mod-mod/i)*inv[mod%i]%mod;
    for(int i=1;i<=n;i++) {
        scanf("%lld%lld",&a[i],&b[i]);
        num[++cnt]=a[i];
        num[++cnt]=b[i]+1;
    }
    sort(num+1,num+1+cnt);
    cnt=unique(num+1,num+1+cnt)-num-1;
    for(int i=1;i<=n;i++) {
        a[i]=lower_bound(num+1,num+1+cnt,a[i])-num;
        b[i]=lower_bound(num+1,num+1+cnt,b[i]+1)-num;
    }
    C[0]=1;
    g[0]=1;
    for(int j=1;j<cnt;j++) {
        int len=num[j+1]-num[j];
        for(int i=1;i<=n;i++)
            C[i]=C[i-1]*(len+i-1)%mod*inv[i]%mod;
        for(int i=n;i>=1;i--) if(a[i]<=j&&b[i]>=j+1) {
            ll f=0,m=1,c=len;
            for(int p=i-1;p>=0;p--) {
                f=(f+c*g[p]%mod)%mod;
                if(a[p]<=j&&j+1<=b[p]) c=C[++m];
            }
            g[i]=(g[i]+f)%mod;
        }
    }
    ll ans=0;
    for(int i=1;i<=n;i++) ans=(ans+g[i])%mod;
    cout<<ans;
}