Submission #1559168

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Source Code Expand

# include <iostream>
# include <algorithm>
# include <vector>
# include <string>
# include <set>
# include <map>
# include <cmath>
# include <iomanip>
# include <functional>
# include <utility>
# include <stack>
# include <queue>
# include <list>
using namespace std;
using LL = long long;
constexpr int MOD = 1000000000 + 7;
constexpr int INF = 2000000000;
const double PI = acos(-1);

bool same[100001];
int main() {
	int n;
	cin >> n;
	int a;
	int ans = 0;
	for (int i = 1; i <= n; i++) {
		cin >> a;
		if (a == i)same[i] = true;
	}
	for (int i = 1; i < n; i++) {
		if (same[i] && same[i + 1]) {
			same[i] = false;
			same[i + 1] = false;
			ans++;
		}
		else if (same[i]) {
			same[i] = false;
			ans++;
		}
	}
	cout << ans << endl;
}

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