#include <bits/stdc++.h>
using namespace std;
using ll = long long;
int n;
ll u, d;
ll x, y;
bool flag;
int main() {
	freopen("domino.in", "r", stdin);
	freopen("domino.out", "w", stdout);
	scanf("%d", &n);
	for (int i = 0; i < n; ++i) {
		scanf("%lld%lld", &x, &y);
		u += x;
		d += y;
		if (x % 2 != y % 2) flag = 1;
	}
	if ((u & 1) ^ (d & 1)) {
		puts("-1");
		return 0;
	}
	if (u % 2 == 0 && d % 2 == 0) {
		puts("0");
		return 0;
	}
	if (flag) {
		puts("1");
	} else {
		puts("-1");
	}
	return 0;
}

#include <bits/stdc++.h>
#define N 1000010
using namespace std;
int tot;
int n;
char s[N];
int len, ans;
int main() {
	freopen("queue.in", "r", stdin);
	freopen("queue.out", "w", stdout);
	scanf("%s", s);
	len = strlen(s);
 {
		int i = 0;
		while (len && s[len - 1] == 'M') --len;
		while (i < len && s[i] == 'F') ++i;
		if (i == len || !len) {
			puts("0");
			return 0;
		}
	}
	for (int i = 0; i < len; ++i) {
		if (s[i] == 'M') ++tot;
		else {
			ans = max(ans + 1, tot);
		}
	}
	printf("%d", ans);
	return 0;
}

#include <bits/stdc++.h>
#define N 100010
using namespace std;
int n, m;
int ans[N], a[N];
vector <pair <int, int> > q[N];
struct que {
	int opt, a, b;
}op[N];
int main() {
	freopen("array.in", "r", stdin);
	freopen("array.out", "w", stdout);
	scanf("%d%d", &n, &m);
	for (int i = 1; i <= n; ++i) scanf("%d", a + i);
	for (int i = 1; i <= m; ++i) {
		scanf("%d%d%d", &op[i].opt, &op[i].a, &op[i].b);
		if (op[i].opt) {
			q[op[i].b].emplace_back(make_pair(i, op[i].a));
		}
	}
	for (auto &i : q[0]) {
		ans[i.first] = a[i.second];
	}
	for (int i = 1; i <= m; ++i) {
		if (!op[i].opt) {
			a[op[i].a] = op[i].b;
		}
		for (auto &j : q[i]) {
			ans[j.first] = a[j.second];
		}
	}
	for (int i = 1; i <= m; ++i) {
		if (op[i].opt) {
			printf("%d\n", ans[i]);
		}
	}
	return 0;
}