#include<bits/stdc++.h> #define ll long long using namespace std; const ll MOD=1e9+7; const int MAXN=1e5+10; int n; ll mui[MAXN],ans; char s[MAXN]; ll Qpow(ll a,ll x){ ll r=1; for(;x;a=a*a%MOD,x>>=1) if(x&1)r=r*a%MOD; return r%MOD; } ll inv(int x){ return Qpow(x,MOD-2); } ll C(int n,int m){ return mui[n]*inv(mui[n-m]*mui[m]%MOD)%MOD; } int main(){ scanf("%d%s",&n,s); mui[0]=1; for(int i=1;i<=n;i++) mui[i]=mui[i-1]*i%MOD; for(int i=0;i<n;i++) ans=(ans+C(n-1,i)*(s[i]-'0'))%MOD; ans=(ans*inv(Qpow(2,n-1)))%MOD; printf("%lld",(1%MOD+MOD-ans)%MOD); return 0; }