#include<bits/stdc++.h>

using namespace std;

#define fRead(x)  freopen(x,"r",stdin)
#define fWrite(x) freopen (x,"w",stdout)

#define LL long long
#define ULL unsigned long long
#define ff first
#define ss second
#define pb push_back
#define INF 2e16
#define PI acos(-1.0)
#define mk make_pair
#define pii pair<int,int>
#define pll pair<LL,LL>


#define min3(a,b,c) min(a,min(b,c))
#define max3(a,b,c) max(a,max(b,c))
#define min4(a,b,c,d) min(a,min(b,min(c,d)))
#define max4(a,b,c,d) max(a,max(b,max(c,d)))
#define SQR(a) ((a)*(a))
#define FOR(i,a,b) for(int i=a;i<=b;i++)
#define ROF(i,a,b) for(int i=a;i>=b;i--)
#define REP(i,b) for(int i=0;i<b;i++)
#define MEM(a,x) memset(a,x,sizeof(a))
#define ABS(x) ((x)<0?-(x):(x))

#define scanI(a) scanf("%d",&a)
#define scanI2(a,b) scanI(a) , scanI(b)
#define scanI3(a,b,c) scanI(a), scanI(b), scanI(c)
#define scanI4(a,b,c,d) scanI(a), scanI(b), scanI(c), scanI(d)

#define scanL(a) scanf("%I64d",&a)
#define scanL2(a,b) scanL(a) , scanL(b)
#define scanL3(a,b,c) scanL(a), scanL(b), scanL(c)
#define scanL4(a,b,c,d) scanL(a), scanL(b), scanL(c), scanL(d)

#define SORT(v) sort(v.begin(),v.end())
#define REV(v) reverse(v.begin(),v.end())
#define MOD 1000000007

#define FastRead ios_base::sync_with_stdio(0);cin.tie(nullptr);
bool Check(int N,int pos) { return (bool)(N&(1<<pos)); }
int Set(int N,int pos) { return (N|(1<<pos)); }

LL BigMod(LL B,LL P,LL M){LL R=1;while(P>0){if(P%2==1){R=(R*B)%M;}P/=2;B=(B*B)%M;}return R;}
//LL fac[100005];
//LL COM(LL a,LL b){return ((fac[a]*BigMod((fac[b]*fac[a-b])%MOD,MOD-2,MOD))%MOD+MOD)%MOD;}

int ara[1005];
int main()
{
    int n;
    cin >> n;
    REP(i,n)cin >> ara[i];
    int mx = 0;

    for(int i = 1;i<=100;i++)
    {
        int cnt = 0;
        REP(j,n)
        {
            if(ara[j]==i or ara[j]==i+1)cnt++;
        }
        mx = max(mx,cnt);
    }
    cout << mx;

}