func_code_string: #include <bits/stdc++.h>   using namespace std;   int c[10000] = {0}, d[10000] = {0};   int main() {     int n, m, i;     scanf( %d%d , &n, &m);     for (i = 0; i < m; i++) {       int x, y;       scanf( %d%d , &x, &y);       c[x]++;       d[y]++;     }     int ans = 0, j, kc = 0, kd = 0;     for (i = 2; i <= n - 1; i++) {       if (!c[i]) ans++;       if (!d[i]) ans++;     }     if (n % 2 == 1 && !c[(n + 1) / 2] && !d[(n + 1) / 2]) ans--;     printf( %d n , ans);     return 0;   }   