func_code_string: #include <bits/stdc++.h>   using namespace std;   const int MOD = (int)1e9 + 7;   const int FFTMOD = 1007681537;   const int INF = (int)1e9;   const long long LINF = (long long)1e18;   const long double PI = acos((long double)-1);   const long double EPS = 1e-9;   inline long long gcd(long long a, long long b) {     long long r;     while (b) {       r = a % b;       a = b;       b = r;     }     return a;   }   inline long long lcm(long long a, long long b) { return a / gcd(a, b) * b; }   inline long long fpow(long long n, long long k, int p = MOD) {     long long r = 1;     for (; k; k >>= 1) {       if (k & 1) r = r * n % p;       n = n * n % p;     }     return r;   }   template <class T>   inline int chkmin(T& a, const T& val) {     return val < a ? a = val, 1 : 0;   }   template <class T>   inline int chkmax(T& a, const T& val) {     return a < val ? a = val, 1 : 0;   }   inline long long isqrt(long long k) {     long long r = sqrt(k) + 1;     while (r * r > k) r--;     return r;   }   inline long long icbrt(long long k) {     long long r = cbrt(k) + 1;     while (r * r * r > k) r--;     return r;   }   inline void addmod(int& a, int val, int p = MOD) {     if ((a = (a + val)) >= p) a -= p;   }   inline void submod(int& a, int val, int p = MOD) {     if ((a = (a - val)) < 0) a += p;   }   inline int mult(int a, int b, int p = MOD) { return (long long)a * b % p; }   inline int inv(int a, int p = MOD) { return fpow(a, p - 2, p); }   inline int sign(long double x) { return x < -EPS ? -1 : x > +EPS; }   inline int sign(long double x, long double y) { return sign(x - y); }   const int maxn = 50 + 5;   int n, p;   int c[maxn];   int f[maxn][maxn];   int p2[maxn];   int dp[maxn][maxn][maxn][2];   int calc(int pos, int u, int v, int fa) {     if (pos == n) return fa == p;     int& res = dp[pos][u][v][fa];     if (~res) return res;     res = 0;     for (int i = (0); i < (2); ++i) {       int num = c[pos] == -1 || c[pos] == i;       if (!num) continue;       int ar[] = {u, v};       for (int j = (0); j < (ar[i ^ 1] + 1); ++j) {         int add = j + 1 & 1;         ar[i] += add;         int nfa = fa + j + 1 & 1;         addmod(res,                mult(p2[pos - ar[i ^ 1]],                     mult(f[j][ar[i ^ 1]], calc(pos + 1, ar[0], ar[1], nfa))));         ar[i] -= add;       }     }     return res;   }   void chemthan() {     for (int i = (0); i < (maxn); ++i) f[0][i] = 1;     for (int i = (1); i < (maxn); ++i)       for (int j = (1); j < (maxn); ++j)         f[i][j] = (f[i][j - 1] + f[i - 1][j - 1]) % MOD;     for (int i = (0); i < (maxn); ++i) p2[i] = fpow(2, i);     cin >> n >> p;     for (int i = (0); i < (n); ++i) cin >> c[i];     memset(dp, -1, sizeof(dp));     cout << calc(0, 0, 0, 0) <<   n ;   }   int main(int argc, char* argv[]) {     ios_base::sync_with_stdio(0), cin.tie(0);     if (argc > 1) {       assert(freopen(argv[1],  r , stdin));     }     if (argc > 2) {       assert(freopen(argv[2],  wb , stdout));     }     chemthan();     cerr <<   nTime elapsed:   << 1000 * clock() / CLOCKS_PER_SEC <<  ms n ;     return 0;   }   