#include "bits/stdc++.h"
using namespace std;
const int N=1e5+20,MOD=(int)(1e9)+7;
int n,l,r,p[N],i;
long long ans;
int main()
{
p[0]=1;
for(i=1;i<N;i++) p[i]=(p[i-1]*2LL)%MOD;
scanf("%d",&n);
for(i=0;i<n;i++)
{
scanf("%d%d",&l,&r);
ans+=1LL*(r-l+1)*p[n-1];
ans%=MOD;
}
printf("%lld",ans);
}
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