func_code_string: #include <bits/stdc++.h>   using namespace std;   template <class T>   inline bool chkmin(T &x, T y) {     return y < x ? x = y, 1 : 0;   }   template <class T>   inline bool chkmax(T &x, T y) {     return x < y ? x = y, 1 : 0;   }   inline long long Max(long long x, long long y) { return x > y ? x : y; }   inline long long Min(long long x, long long y) { return x < y ? x : y; }   int n, m;   int res;   map<int, int> lck;   map<int, int>::iterator it;   long long fac[100002], inv[100002];   long long dp[100002];   void Add(long long &x, long long y) {     x += y;     if (x >= 1000000007)       x -= 1000000007;     else if (x < 0)       x += 1000000007;   }   bool check(int x) {     while (x) {       if (x % 10 != 4 && x % 10 != 7) return 0;       x /= 10;     }     return 1;   }   void Init() {     fac[0] = fac[1] = 1;     inv[0] = inv[1] = 1;     for (int i = (2), i_end_ = (100002); i < i_end_; i++)       fac[i] = fac[i - 1] * i % 1000000007;     for (int i = (2), i_end_ = (100002); i < i_end_; i++)       inv[i] = (1000000007 - (1000000007 / i)) * inv[1000000007 % i] % 1000000007;     for (int i = (2), i_end_ = (100002); i < i_end_; i++)       inv[i] = inv[i] * inv[i - 1] % 1000000007;   }   long long C(int n, int m) {     if (n < 0 || m > n) return 0;     return fac[n] * inv[m] % 1000000007 * inv[n - m] % 1000000007;   }   int main() {     Init();     scanf( %d%d , &n, &m);     for (int i = (1), i_end_ = (n); i <= i_end_; i++) {       int x;       scanf( %d , &x);       if (check(x))         lck[x]++;       else         res++;     }     int tot = 0;     dp[0] = 1;     for (it = lck.begin(); it != lck.end(); it++) {       tot++;       for (int i = (min(tot, m)), i_end_ = (1); i >= i_end_; i--)         Add(dp[i], dp[i - 1] * it->second % 1000000007);     }     long long ans = 0;     for (int i = (0), i_end_ = (min(tot, m)); i <= i_end_; i++)       Add(ans, dp[i] * C(res, m - i) % 1000000007);     printf( %I64d n , ans);     return 0;   }   