#include <bits/stdc++.h> using namespace std; typedef long long ll; const int maxn = 1e6+50; const ll INF = 0xffffffff; int main() { int n; cin>>n; double x[3005],y[3005]; for(int i=1;i<=n;i++) cin>>x[i]>>y[i]; int f = 0, ans = -1; for(int i=1;i<=n;i++) { double dis = 0; f = 1; for(int j = 1;j<=n;j++) { if(i==j)continue; if(!dis) { dis = sqrt((x[i]-x[j])*(x[i]-x[j]) + (y[i]-y[j])*(y[i]-y[j])); } else { if(dis!=sqrt((x[i]-x[j])*(x[i]-x[j]) + (y[i]-y[j])*(y[i]-y[j]))) { f = 0; break; } } } if(f) { ans = i; break; } } cout<<ans<<endl; } |
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