Go: package main

import (
	"bufio"
	"fmt"
	"os"
	"sort"
	"strconv"
)

func main() {
	mountHeightList := make([]int64, 10)
	scanner := bufio.NewScanner(os.Stdin)
	for i := 0; i < 10; i++ {
		scanner.Scan()
		mountHeightList[i], _ = strconv.ParseInt(scanner.Text(), 10, 64)
	}

	sort.Slice(mountHeightList, func(i, j int) bool { return mountHeightList[i] > mountHeightList[j] })

	for i := 0; i < 3; i++ {
		fmt.Printf("%d\n", mountHeightList[i])
	}
}

C++: // Bismillahir Rahmanir Rahim

#include <bits/stdc++.h>
using namespace std;

typedef long long int ll;
typedef unsigned long long int ull;
typedef long double ld;
typedef vector <int> vi;
typedef vector <ll> vl;
typedef pair <ll, ll> pll;
typedef pair <ll, pll> plp;
typedef pair <int, int> pii;
typedef pair <int, pii> pip;
typedef map <int, vector<int> > mvi;
typedef map <ll, vector<ll> > mvl;

const int MX = 2e6+10;
const int mod = 1e9 + 7;
const ll inf = 1LL << 62;

int dx4[] = { 0, 0, -1, 1 };
int dy4[] = { 1, -1, 0, 0 };

int dx[] = { 1, 1, 1, 0, 0, -1, -1, -1 };
int dy[] = { 1, 0, -1, 1, -1, 1, 0, -1 };

// TOOLS
#define LCM(a,b)        (a / __gcd(a,b) ) *b
#define gcd(a,b)        __gcd(a,b)
#define all(x)          (x).begin(), (x).end()
#define mem(a, n)       memset(a, n, sizeof(a))
#define for1(i, n)      for(int i=1; i<=n; i++)
#define for0(i, n)      for(int i=0; i<n; i++)
#define rof0(i, n)      for(int i=n-1; i>=0; i--)
#define rof1(i, n)      for(int i=n; i>=1; i--)
#define forab(i, a, b)  for(int i=a; i<=b; i++)
#define rofab(i, a, b)  for(int i=b; i>=a; i--)
#define pb              push_back
#define pbb             pop_back

// CIN/COUT
#define YES             cout << "YES" << endl
#define NO              cout << "NO" << endl
#define sin(s)          getline(cin, s)
#define scf(a)          cin >> a
#define scf2(a, b)      cin >> a >> b
#define scf3(a, b, c)   cin >> a >> b >> c
#define scf4(a,b,c,d)   cin >> a >> b >> c >> d
#define pnf(a)          cout << (a) << endl
#define pnf2(a, b)      cout << (a) << " " << (b) << endl
#define pnf3(a, b, c)   cout << (a) << " " << (b) << " " << (c) << endl
#define bug(n)          cout << ">> " << n << " <<" << endl
#define line            cout << "==========" << endl
#define pnfa(a)         cout << (a) << " "
#define pf(a)           cout << (a)
#define sp              cout << " "
#define nl              cout << endl
#define Cas(a)              cout << "Case "<<(a)<<": "

// SCANF/PRINTF
#define fYES            printf("YES\n")
#define fNO             printf("NO\n")
#define Sin(s)          gets(s)
#define Scf(a)          scanf("%lld", &a)
#define Scf2(a, b)      scanf("%lld %lld", &a, &b)
#define Scf3(a, b, c)   scanf("%lld %lld %lld", &a, &b, &c)
#define Scf4(a,b,c,d)   scanf("%lld %lld %lld %lld", &a, &b, &c, &d)
#define Pnf(a)          printf("%lld\n", a)
#define Pnf2(a, b)      printf("%lld %lld\n", a, b)
#define Pnf3(a, b, c)   printf("%lld %lld %lld\n", a, b, c)
#define Bug(n)          printf(">> %lld <<\n", n)
#define Line            printf("==========\n")
#define Pnfa(a)         printf("%lld ", a)
#define Pf(a)           printf("%lld", a)
#define Sp              printf(" ")
#define Nl              printf("\n")

// OTHERS
#define saz(n)          n.size()
#define clr(v)          v.clear()
#define min3(a, b, c)   min(a, min(b, c))
#define max3(a, b, c)   max(a, max(b, c))
#define in              freopen("input.txt", "r", stdin)
#define out             freopen("output.txt", "w", stdout)
#define FastIO          { ios_base::sync_with_stdio(false); cin.tie(0); }
#define F               first
#define S               second
#define mpp             make_pair

//string s;
//vector<ll> v;
//vector<ll> v[MX];
//ll ar[MX], br[MX];
//ll vist[MX];
//map<ll,ll> mp;

int main()
{

    ll n, m, k, q, t, cnt = 0, sum = 0,ans=0, mx = -inf, mn = inf, a, b, c,d,e,f,g,h,i,j ,x, y, z,temp, temp1;
    string s, s1, s2, s3;
    vector<int> v;
    for0(i,10)
    {
        cin>>a;
        v.pb(a);
    }
    sort(all(v));
    int len=v.size()-1;
    cout<<v[len]<<endl<<v[len-1]<<endl<<v[len-2]<<endl;

    return 0;
}

C++: #include <iostream>
#include <vector>
#include <map>
#include <set>
#include <algorithm>
#include <queue>
#include <stack>
#include <cmath>
#include <cstdio>
#include <string>
#include <sstream>

using namespace std;

#define rep(i, n) for(int i = 0; i < (int)n; ++i)
#define repn(i, n) for(int i = 1; i <= (int)n; ++i)
#define pb push_back
#define lb lower_bound
#define mp make_pair
#define ite iterator
#define max2(x, y) ((x) > (y)) ? (x) : (y)
#define max3(x,y,z) max2((x), max2((y),(z)))
#define max4(v,w,x,y) max2(max2((v),(w)), max2((x),(y)))
#define min2(x, y) ((x) > (y)) ? (y) : (x)
#define min3(x,y,z) min2((x), min2((y),(z)))
#define min4(v,w,x,y) min2(min2((v),(w)), min2((x),(y)))
#define ul unsigned long
#define ull unsigned long long
#define INF 1000000007
#define MOD 1000000007
#define fs first
#define sd second

template<typename T>
bool elem(set<T> st, T val){
	return (st.find(val) != st.end());
}

template<typename T>
void printv(vector<T> vt){
    rep(i, vt.size() - 1)
        cout << vt[i] << " ";
    cout << vt[vt.size() - 1] << endl;
}

typedef vector<int> vint;
typedef vector<ul> vul;
typedef vector<ull> vull;
typedef pair<int, int> pii;

int main(void){
    vint a;
    int d;
    while(cin >> d) a.pb(d);
    sort(a.begin(), a.end(), greater<int>());
    rep(i, 3)
        cout << a[i] << endl;
    return 0;
}

C++: #include <iostream>
using namespace std;

int main()
{
  int high;
  int temp1,temp2;
  int first=0,second=0,third=0;
  
  for(int i=0;i<10;i++){
    cout<<"山の高さ"<<i<<":";
    cin>>high;
    if(high>first){
      temp1=first;
      first=high;
      temp2=second;
      second=temp1;
      third=temp2;
    } else if (first>=high && high>second){
      temp2=second;
      second=high;
      third=temp2;
    } else if (second>=high && high>third){
      third=high;
    }
  }

  cout<<"1番目に高い山の高さ:"<<first<<endl;
  cout<<"2番目に高い山の高さ:"<<second<<endl;
  cout<<"3番目に高い山の高さ:"<<third<<endl;
  
  return 0;
}

C++: #include <bits/stdc++.h>
using namespace std;
int main()
{
    vector<int>vec;
    for(int i = 0;i < 10;++i)
    {
        int v; cin << v;
        vec.push_back(v);
    }
    sort(vec.begin(),vec.end());
    cout << vec[9] <<endl<< vec[8] <<endl << vec[7] <<endl;
    return 0;
}

C++: #include <iostream>

int main(){
	int m,mf=0,ms=0,mt=0;
	for(int a=0;a<10;a++){
		std::cin>>m;
		if(m>mf){
			mt=ms;
			ms=mf;
			mf=m;
			m=0;
	    }
		if(m>ms){
			mt=ms;
			ms=m;	
			m=0;
		}
			
		if(m>mt){
			mt=m;
			
		}
			
		
	}
	std::cout<<mf<<std::endl<<ms<<std::endl<<mt;
	return 0;
}

C++: #include<stdio.h>
         
int main(void){
    /* 宣言と初期化 */
    int hai[10];
    int id[2];
    int i;
    int temp2nd;
    int temp3rd;
    int tempmax;
         
for(i=0;i<10;i++)
{
scanf("%d",&hai[i]);
}
    /* 代入 */
    temp2nd=hai[0];
    tempmax=hai[0];
    temp3rd=hai[0]; 
    /* 計算 */
    for(i=0;i<10;i++){
        /* 最大値求める */
        if(hai[i]>tempmax)
       {tempmax=hai[i];id[0]=i;}
    }
    for(i=0;i<10;i++){
        /*2番目求める */
        if(hai[i]<tempmax&&hai[i]>temp2nd&& i=! id[0])
        {temp2nd=hai[i];id[1]=i;}
    }   
    for(i=0;i<10;i++){
        /* 3番目求める */
        if(hai[i]>temp3rd&&hai[i]<temp2nd && i =! id[1] && i =! id[0])
       {temp3rd=hai[i];}
    }
         
    /* 表示 */
    printf("最も高い山の高さ　%d\n",tempmax);
    printf("２番目に高い山の高さ　%d\n",temp2nd);
    printf("３番目に高い山の高さ　%d\n",temp3rd);
         
    return 0;
}

C++: #include<iostream>
using namespace std;
int main(){
  int array[10],tmp;
  for(int i = 0;i<10;i++)
    cin >> array[i];
  for(int i=0;i<10;i++){
    for(int k=0;k<9;k++){
      if(array[k] < array[k+1]){
	tmp = array[k]; array[k] = array[k+1]; array[k+1] = tmp;
      }
    }
  }
  for(int i =0 ;i< 3;i++){
    cout << array[i] << endl;
} 
}