#include using namespace std; typedef long long ll; typedef pair ii; #define pii 3.141592654 #define INF 1000000007 #define N 105 #define M 10 #define F first #define S second #define pb push_back #define mp make_pair #define si(x) scanf("%d",&x) #define sif(x) scanf("%lf",&x) #define sil(x) scanf("%I64d",&x) #define pi(x) printf("%d\n",x) #define pis(x) printf("%d ",x) #define cpi(x) printf("Case %d: ",x) #define pil(x) printf("%I64d\n",x) #define rep(i,n,m) for(int i = n; i< m; i++) #define reps(i,n,m) for(int i = n; i >= m; i--) #define lft(x) x*2 #define rgt(x) x*2+1 int n,a[N],x,mx; int main() { si(n); rep(i,0,n){ si(x); a[x]++; } rep(i,1,100){ mx = max(a[i]+a[i+1],mx); } pi(mx); return 0; }