#include using namespace std; typedef signed long long ll; #undef _P #define _P(...) (void)printf(__VA_ARGS__) #define FOR(x,to) for(x=0;x class MaxFlow_dinic { public: struct edge { int to,reve;V cap;}; static const int MV = 1100; vector E[MV]; int itr[MV],lev[MV]; void add_edge(int x,int y,V cap,bool undir=false) { E[x].push_back((edge){y,(int)E[y].size(),cap}); E[y].push_back((edge){x,(int)E[x].size()-1,undir?cap:0}); } void bfs(int cur) { MINUS(lev); queue q; lev[cur]=0; q.push(cur); while(q.size()) { int v=q.front(); q.pop(); ITR(e,E[v]) if(e->cap>0 && lev[e->to]<0) lev[e->to]=lev[v]+1, q.push(e->to); } } V dfs(int from,int to,V cf) { if(from==to) return cf; for(;itr[from]cap>0 && lev[from]to]) { V f=dfs(e->to,to,min(cf,e->cap)); if(f>0) { e->cap-=f; E[e->to][e->reve].cap += f; return f; } } } return 0; } V maxflow(int from, int to) { V fl=0,tf; while(1) { bfs(from); if(lev[to]<0) return fl; ZERO(itr); while((tf=dfs(from,to,numeric_limits::max()))>0) fl+=tf; } } }; int N; int A[1010]; int R[1010]; void solve() { int i,j,k,l,r,x,y; string s; cin>>N; MaxFlow_dinic mf; FOR(i,N) { mf.add_edge(0,i+1,1); mf.add_edge(i+1+N,200,1); cin>>A[i]; FOR(x,N) if(x!=A[i]) mf.add_edge(i+1,N+1+x,1); } x=mf.maxflow(0,200); if(x=N+1 && r.to<=2*N && r.cap==0) x=r.to-N-1; } _P("%d\n",x); } } int main(int argc,char** argv){ string s;int i; if(argc==1) ios::sync_with_stdio(false); FOR(i,argc-1) s+=argv[i+1],s+='\n'; FOR(i,s.size()) ungetc(s[s.size()-1-i],stdin); solve(); return 0; }