```
#include<bits/stdc++.h>
using namespace std;
int sans[132444],chara[32637];
int main(){
int n;
scanf("%d",&n);
for(int i=1;i<=n;i++){
scanf("%d",&sans[i]);chara[sans[i]]++;
}
int jojo=0;
for(int i=1;i<n;i++){
for(int j=i+1;j<=n;j++){
if(sans[i]!=sans[j]){
jojo+=chara[sans[i]+sans[j]];chara[sans[i]+sans[j]]=0;
}
}
}
printf("%d",jojo);
return 0;
}
by Epic_sans @ 2023-11-08 13:06:35
@[Dream_liu](/user/1047750)
by Epic_sans @ 2023-11-08 13:08:43
@[Epic_sans](/user/1071583) 谢谢：）
by Dream_liu @ 2023-11-08 22:17:48