func_code_string: #include <bits/stdc++.h>   using namespace std;   int main(void) {     int n;     cin >> n;     int a, b;     int s1 = 0;     int s2 = 0;     int flag = 0;     while (n--) {       cin >> a >> b;       if ((a & 1) != (b & 1)) flag = 1;       s1 += a;       s2 += b;     }     cerr << s1 <<     << s2 << endl;     int ans = 0;     if (s1 % 2 != s2 % 2) {       ans = -1;     } else {       if (s1 % 2 == 0)         ans = 0;       else if (!flag)         ans = -1;       else         ans = 1;     }     cout << ans << endl;     return 0;   }   