#include <iostream>

using namespace std;

int main()
{
    ios::sync_with_stdio(false);
    int N;
    while(true)
    {
        cin>>N;
        if(cin.good()==false)
        {
            return 0;
        }

        int * nums = new int[N];
        //int * solved = new int[N];
        for(int i=0;i<N;i++)
        {
            cin>>nums[i];
            //solved = 0;
        }

        int result = 0;

        for(int i=0;i<N;i++)
        {
            if(i+1 != nums[i])
            {
                //cout<<i+1<<" not "<<nums[i]<<endl;
                int temp=nums[i];
                nums[i]=nums[temp-1];
                nums[temp-1]=temp;
                result++;
                //cout<<"Swapped "<<temp<<" "<<nums[i]<<endl;
                i--;
            }
        }
        delete [] nums;
        cout<<result<<endl;


    }
    return 0;
}