#include using namespace std; typedef long long LL; const int mod = 1e9 + 7; /* 测试用例: 10000000 10000000 答案: 999300007 */ //快速乘,计算a*b%mod LL ksc(LL a, LL b) { LL ans = 0; a %= mod; while (b) { if (b & 1) ans = (ans + a) % mod; b >>= 1; //位运算,右移1位,相当于除以2 a = (a + a) % mod; } return ans; } int main() { LL a, b; cin >> a >> b; printf("%lld\n", ksc(a, b)); return 0; }