Optimal page replacement algorithm in c++

#include<bits/stdc++.h>
using namespace std;
int main()
{
    int f,p,j=0,x,pf=0,h=0,m,i,index,u,e=0,w,g;
    int arr[1000]={0};
    vector<int>o;
    std::vector<int>::iterator it;

    cout<<"Enter no of pages"<<endl;
    cin>>p;
    cout<<"Enter the reference string"<<endl;
    for(i=0;i<p;i++)
    {
        cin>>x;
        o.push_back(x);
    }
    cout<<"Enter no of frames"<<endl;
    cin>>f;
    vector<int>a(f,-1);
    while(j<p)
    {
        m=0,e=0,g=0;
        if(j<=f-1)
    {
        x=o.at(j);
        a.at(j)=x;
        ++pf;
    }
        else
    {
            if(find(a.begin(), a.end(), o.at(j))!=a.end())
            {
                ++h;
            }
            else
        {
                for(i=0;i<f;i++)
            {
                    if(find(o.begin()+j+1,o.end(),a.at(i))!=o.end())
                {
                    it=find(o.begin()+j+1,o.end(),a.at(i));
                    if(it-o.begin()>m && e==0)
                    {
                            m=(it-o.begin());index=i;
                    }
                }
                else
                {
                    index=i;
                    ++e;
                    if(e>=2)
                    {
                        for(w=0;w<f;w++)
                        {
                            if(arr[a[w]]>=g){g=arr[a[w]];index=w;}
                        }
                        break;
                    }
                }
           }
            x=o.at(j);
            arr[a[index]]=0;
            a.at(index)=x;
            ++pf;
        }
    }
            for(i=0;i<f;i++)
        {
            ++arr[a[i]];
            cout<<a[i]<<" ";
        }
        cout<<endl;
        ++j;
    }
    cout<<"No of page faults happen "<<pf<<endl;
    cout<<"No of page hit happen "<<h;
}
/*output:
Enter no of pages
20
Enter the reference string
1 2 3 4 2 5 3 4 2 6 7 8 7 9 7 8 2 5 4 9
Enter no of frames
3
1 -1 -1
1 2 -1
1 2 3
4 2 3
4 2 3
4 5 3
4 5 3
4 5 3
4 5 2
6 5 2
7 5 2
7 8 2
7 8 2
7 8 9
7 8 9
7 8 9
2 8 9
2 5 9
2 5 4
9 5 4
No of page faults happen 14
No of page hit happen 6
20
Enter the reference string
1 2 3 4 2 5 3 4 2 6 7 8 7 9 7 8 2 5 4 9
Enter no of frames
4
1 -1 -1 -1
1 2 -1 -1
1 2 3 -1
1 2 3 4
1 2 3 4
5 2 3 4
5 2 3 4
5 2 3 4
5 2 3 4
5 2 6 4
5 2 7 4
5 2 7 8
5 2 7 8
9 2 7 8
9 2 7 8
9 2 7 8
9 2 7 8
9 5 7 8
9 5 4 8
9 5 4 8
No of page faults happen 11
No of page hit happen 9*/