CSES-1617 Bit Strings

#include <bits/stdc++.h>
using namespace std;

#define pb push_back
#define fi first
#define se second
#define INF LONG_LONG_MAX/1000
#define WA() cin.tie(0)->sync_with_stdio(0)
#define all(x) (x).begin(), (x).end()
#define int long long
#define PII pair<int, int>

signed main() { WA();
    int n, a = 1;
    cin >> n;
    while (n--) {
        a <<= 1;
        a %= (int)1e9+7;
    }
    cout << a;
}