Submission #1559167

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Source Code Expand

#include <iostream>
#include <iomanip>
#include <cstdio>
#include <cstring>
#include <cmath>
#include <cstdlib>
#include <algorithm>
#include <string>
#include <vector>
#include <stack>
#include <queue>
#include <set>
#include <map>
#include <functional>
#include <utility>
#include <tuple>
#include <cctype>
#define INF 0x3f3f3f3f
#define MOD 1000000007
#define PI 4*atan(1.0)
typedef long long ll;
typedef long double ld;
using namespace std;
int dx[4]={0,0,-1,1};
int dy[4]={-1,1,0,0};
const int SIZE=100050;
//int arr[SIZE]={};
//ここまでテンプレ
int main(){
	int N;
	cin>>N;
	int ans=0,ren=0;
	for(int i=0;i<N;i++){
		int p;
		cin>>p;
		if(p==i+1)
			ren++;
		else{
			ans+=(ren+1)/2;
			ren=0;
		}
		//cout<<ren<<endl;
	}
	ans+=(ren+1)/2;
	ren=0;
	cout<<ans<<endl;
	return 0;
}

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