#include <iostream>
#include <sstream>
#include <iomanip>
#include <vector>
#include <string>
#include <map>
#include <set>
#include <algorithm>
#include <numeric>
#include <iterator>
#include <functional>
#include <complex>
#include <queue>
#include <stack>
#include <cmath>
#include <cassert>
#include <tuple>
using namespace std;
typedef long long LL;
typedef complex<double> CMP;
class StoryFromTCO { public:
int minimumChanges(vector <int> places, vector <int> cutoff)
{
const int N = places.size();
vector<pair<int,int>> cp;
for(int i=0; i<N; ++i)
cp.emplace_back(cutoff[i], places[i]);
sort(cp.begin(), cp.end());
vector<int> lm(N); // i-th place candidate can be put at >=lm[i]
for(int i=0; i<N; ++i) {
int p=cp[i].second, k=0;
for(; k<N; ++k)
if(p <= cp[k].first)
break;
if(k == N)
return -1;
lm[i] = k;
}
return solve(lm);
}
// reorder v so that v[i]<=i for all i.
int solve(vector<int> v)
{
const int N = v.size();
const int HOLE = 0x7fffffff;
int ans = 0;
multiset<int> stock;
for(int i=0; i<N; ++i)
if(!(v[i]<=i)) {
if(stock.empty() || !(*stock.begin()<=i)) {
// find right most fitting elem.
for(int k=N-1; k>i; --k)
if(v[k]<=i) {
stock.insert(v[k]);
v[k] = HOLE;
break;
}
}
if(stock.empty() || !(*stock.begin()<=i))
return -1;
++ans;
if(v[i] != HOLE) stock.insert(v[i]);
v[i] = *stock.begin();
stock.erase(stock.begin());
}
return ans;
}
};
// BEGIN CUT HERE
#include <ctime>
double start_time; string timer()
{ ostringstream os; os << " (" << int((clock()-start_time)/CLOCKS_PER_SEC*1000) << " msec)"; return os.str(); }
template<typename T> ostream& operator<<(ostream& os, const vector<T>& v)
{ os << "{ ";
for(typename vector<T>::const_iterator it=v.begin(); it!=v.end(); ++it)
os << '\"' << *it << '\"' << (it+1==v.end() ? "" : ", "); os << " }"; return os; }
void verify_case(const int& Expected, const int& Received) {
bool ok = (Expected == Received);
if(ok) cerr << "PASSED" << timer() << endl; else { cerr << "FAILED" << timer() << endl;
cerr << "\to: \"" << Expected << '\"' << endl << "\tx: \"" << Received << '\"' << endl; } }
#define CASE(N) {cerr << "Test Case #" << N << "..." << flush; start_time=clock();
#define END verify_case(_, StoryFromTCO().minimumChanges(places, cutoff));}
int main(){
CASE(0)
int places_[] = {20,100,500,50};
vector <int> places(places_, places_+sizeof(places_)/sizeof(*places_));
int cutoff_[] = {7500,2250,150,24};
vector <int> cutoff(cutoff_, cutoff_+sizeof(cutoff_)/sizeof(*cutoff_));
int _ = 3;
END
CASE(1)
int places_[] = {5,4,3,2,1};
vector <int> places(places_, places_+sizeof(places_)/sizeof(*places_));
int cutoff_[] = {5,4,3,2,1};
vector <int> cutoff(cutoff_, cutoff_+sizeof(cutoff_)/sizeof(*cutoff_));
int _ = 0;
END
CASE(2)
int places_[] = {1,5,5,5};
vector <int> places(places_, places_+sizeof(places_)/sizeof(*places_));
int cutoff_[] = {8,6,4,2};
vector <int> cutoff(cutoff_, cutoff_+sizeof(cutoff_)/sizeof(*cutoff_));
int _ = -1;
END
CASE(3)
int places_[] = {3,1,5};
vector <int> places(places_, places_+sizeof(places_)/sizeof(*places_));
int cutoff_[] = {6,4,2};
vector <int> cutoff(cutoff_, cutoff_+sizeof(cutoff_)/sizeof(*cutoff_));
int _ = 3;
END
CASE(4)
int places_[] = {14,11,42,9,19};
vector <int> places(places_, places_+sizeof(places_)/sizeof(*places_));
int cutoff_[] = {11,16,37,41,47}
;
vector <int> cutoff(cutoff_, cutoff_+sizeof(cutoff_)/sizeof(*cutoff_));
int _ = 4;
END
CASE(5)
int places_[] = {4,1,3,3,2,4,5,5,4,4};
vector <int> places(places_, places_+sizeof(places_)/sizeof(*places_));
int cutoff_[] = {3,3,5,2,4,4,5,4,3,5};
vector <int> cutoff(cutoff_, cutoff_+sizeof(cutoff_)/sizeof(*cutoff_));
int _ = 6;
END
CASE(6)
int places_[] = {213,177,237,444,497,315,294,104,522,635,13,26,22,276,88,249,374,17,42,245,80,553,121,625,62,105,
53,132,178,250,18,210,492,181,2,99,29,21,62,218,188,584,702,63,41,79,28,452,2};
vector <int> places(places_, places_+sizeof(places_)/sizeof(*places_));
int cutoff_[] = {33,40,41,48,74,84,117,125,126,164,197,197,201,218,222,231,244,277,290,309,321,321,360,376,440,
442,465,477,491,513,639,645,647,675,706,710,726,736,736,765,801,838,845,854,863,865,887,902,908};
vector <int> cutoff(cutoff_, cutoff_+sizeof(cutoff_)/sizeof(*cutoff_));
int _ = 23;
END
/*
CASE(7)
int places_[] = ;
vector <int> places(places_, places_+sizeof(places_)/sizeof(*places_));
int cutoff_[] = ;
vector <int> cutoff(cutoff_, cutoff_+sizeof(cutoff_)/sizeof(*cutoff_));
int _ = ;
END
CASE(8)
int places_[] = ;
vector <int> places(places_, places_+sizeof(places_)/sizeof(*places_));
int cutoff_[] = ;
vector <int> cutoff(cutoff_, cutoff_+sizeof(cutoff_)/sizeof(*cutoff_));
int _ = ;
END
*/
}
// END CUT HERE