Can anyone tell me why a segmentation fault is occurring?
#include<iostream>
#include<cstdio>
using namespace std;
int main()
{
long int n1,n2,n3;
cin >> n1 >> n2 >> n3;
long int id[100001] = {0};
long int n;
for(long int i = 1;i <= n1+n2+n3;i++)
{
scanf("%d",&n);
id[n]++;
}
long int ans = 0;
for(long int i = 0;i < 100001;i++)
if(id[i] >= 2) ans++;
cout << ans << endl;
for(long int i = 0;i < 100001;i++)
if(id[i] >= 2) cout << i << endl;
return 0;
}