Codeforces Round #593 (Div. 2) B. Alice and the List of Presents 组合数学

B. Alice and the List of Presents

input

1 3

output

7

code

//Siberian Squirrel
#include<bits/stdc++.h>

#define IO ios::sync_with_stdio(false);cin.tie(0);cout.tie(0)
//#define ACM_LOCAL

using namespace std;
typedef long long ll;

const int N = 2e5 + 10;
const int MOD = 1e9 + 7;

ll quick_pow(ll ans, ll p, ll res = 1) {
    
    
    for(; p; p >>= 1, ans = ans * ans % MOD)
        if(p & 1) res = res * ans % MOD;
    return res % MOD;
}

inline void solve(int n, int m, ll res = 0, ll ans = 0) {
    
    
    ans= (quick_pow(2, m) - 1 + MOD) % MOD;
    res = quick_pow(ans, n);
    cout << res << endl;
}

int main() {
    
    
    IO;
#ifdef ACM_LOCAL
    freopen("input", "r", stdin);
    freopen("output", "w", stdout);
#endif
    int o = 1, n, m, k;
//    cin >> o;
    while(o --) {
    
    
        cin >> n >> m;
        solve(n, m);
    }
    return 0;
}