#include <cstdio>

#include <cassert>
template<long size, long mod>
struct smallCombinationTable {
  long table[size][size];
  smallCombinationTable() {
    table[0][0] = 1;
    for(int i = 1; i < size; ++i) {
      table[i][0] = table[i][i] = 1;
      for(int j = 1; j < i; ++j) {
        table[i][j] = (table[i-1][j-1] + table[i-1][j]) % mod;
      }
    }
  }
  long operator() (long n, long r) {
    assert( 0 <= n and n < size );
    assert( 0 <= r and r < size );
    return table[n][r];
  }
};

template<long size, long mod> 
struct factorialTable {
  long table[size];
  factorialTable() {
    table[0] = 1;
    for(int i = 1; i < size; ++i) {
      table[i] = (table[i-1] * i) % mod;
    }
  }
  long operator() (long n) {
    assert( 0 <= n and n < size );
    return table[n];
  }
};

template<typename T>
T pow(T x, long n) {
  T res = 1;
  T p = x;
  while( n != 0 ) {
    if( n & 0x01 ) res *= p;
    p *= p;
    n >>= 1;
  }
  return res;
}

template<long P = 1000000007>
struct Mod {
  Mod() : a(0) {}
  Mod(long x) : a(x) {}
  long get() { return a; }
  Mod operator + (Mod x) { return Mod<P>((a + x.get()) % P); }
  Mod operator += (Mod x) { a = (a + x.get()) % P; return *this; }
  Mod operator - (Mod x) { return Mod<P>((a + P - x.get()) % P); }
  Mod operator -= (Mod x) { a = (a + P - x.a) % P; return *this; }
  Mod operator * (Mod x) { return Mod<P>((a * x.get()) % P); }
  Mod operator *= (Mod x) { a = (a * x.a) % P; return *this; }
  Mod operator / (Mod x) { return *this * pow(x, P - 2); }
  Mod operator /= (Mod x) { a = (*this * pow(x, P - 2)); return *this; }
  long a;
};

template<long size, long mod>
struct Combination {
  factorialTable<size, mod> factorial;
  long operator() (long n, long r) {
    Mod<mod> res = Mod<mod>(factorial(n)) / Mod<mod>(factorial(r) * factorial(n-r));
    return res.get();
  }
};
Combination<1123456, 1000000007> combination;

int main() {
  long m;
  long temp;
  long total = 0;
  long count = 0;
  scanf("%ld\n", &m);
  for(;;) {
    int c = getchar();
    if( c == '\n' ) break;
    ungetc(c, stdin);
    scanf("%ld", &temp);
    total += temp;
    count += 1;
  }
  if( count == 1 and total == 0 ) {
    printf("1\n");
    return 0;
  }
  long n = count + 1;
  long r = m - total - (count - 1);
  // printf("(n, r) = (%ld, %ld)\n", n, r);
  if( r < 0 ) {
    printf("NA\n");
    return 0;
  }
  printf("%ld\n", combination(n + r - 1, r));
  
  return 0;
}