Submission #1558488

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Source Code Expand

#include "iostream"
#include "climits"
#include "list"
#include "queue"
#include "stack"
#include "set"
#include "functional"
#include "algorithm"
#include "string"
#include "map"
#include "iomanip"
#include "random"

using namespace std;

const long long int MOD = 1000000007;
const long double EPS = 0.00000001;
const long double PI = 3.1415926535897932384626433;

long long int N, M, K, L, R, H, W;



int main() {
	ios::sync_with_stdio(false);
	cin.tie(0);
	cin >> N;
	int num[200000] = {};
	for (int i = 0; i < N; i++) {
		cin >> num[i];
	}
	for (int i = 1; i < N; i++) {
		if (num[i - 1] == i) {
			swap(num[i - 1], num[i]);
			M++;
		}
	}
	for (int i = N - 1; i > 0; i--) {
		if (num[i] == i + 1) {
			swap(num[i - 1], num[i]);
			M++;
		}
	}
	cout << M << endl;
	return 0;
}

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