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#include<iostream>
#include<algorithm>
#include<cstdio>
#include<string>
using namespace std;
long long d[110],a[110];
int x=1e9+7;
int main()
{
    int n;
    scanf("%lld",&n);d[1]=0;d[2]=1;a[1]=2;
    for(int i=2;i<=n;i++)
        a[i]=a[i-1]*2%x;
    for(int i=3;i<=n;i++)
        d[i]=(a[i-2]+d[i-1]+d[i-2])%x;
    printf("%lld\n",d[n]);
}
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