Go: package main

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

func main() {
        fp := os.Stdin
        scanner := bufio.NewScanner(fp)
        var lst [3]int

        for scanner.Scan() {
                num, _ := strconv.Atoi(scanner.Text())
                if lst[0] < num {
                        lst[2] = lst[1]
                        lst[1] = lst[0]
                        lst[0] = num
                } else if lst[1] < num {
                        lst[2] = lst[1]
                        lst[1] = num
                } else if lst[2] < num {
                        lst[2] = num
                }
        }

        for _, i := range lst {
                fmt.Printf("%d\n", i)
        }
}

C++: #include <iostream>
#include <vector>
#include <algorithm>

using namespace std;

int main(){
    vector <int> v;
    int a;    
    for(int i=0;i<10;i++){
        cin >> a;
        v.push_back(a);
    }

    sort(v.begin(),v.end());

    cout << v[0] << endl << v[1] << endl << v[2] << endl;

    return 0;

}

C++: // Header {{{
// includes {{{
#include <algorithm>
#include <cassert>
#include <cctype>
#include <climits>
#include <cmath>
#include <complex>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <ctime>
#include <iostream>
#include <iterator>
#include <limits>
#include <list>
#include <map>
#include <numeric>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <sys/time.h>
#include <unistd.h>
#include <vector>
// }}}
using namespace std;
// consts {{{
static const int INF = 1e9;
static const double PI = acos(-1.0);
static const double EPS = 1e-10;
// }}}
// typedefs {{{
typedef long long int LL;
typedef unsigned long long int ULL;
typedef vector<int> VI;
typedef vector<VI> VVI;
typedef vector<LL> VLL;
typedef vector<VLL> VVLL;
typedef vector<ULL> VULL;
typedef vector<VULL> VVULL;
typedef vector<double> VD;
typedef vector<VD> VVD;
typedef vector<bool> VB;
typedef vector<VB> VVB;
typedef vector<char> VC;
typedef vector<VC> VVC;
typedef vector<string> VS;
typedef vector<VS> VVS;
typedef pair<int, int> PII;
typedef complex<int> P;
// }}}
// macros & inline functions {{{
// syntax sugars {{{
#define FOR(i, b, e) for (typeof(e) i = (b); i < (e); ++i)
#define FORI(i, b, e) for (typeof(e) i = (b); i <= (e); ++i)
#define REP(i, n) FOR(i, 0, n)
#define REPI(i, n) FORI(i, 0, n)
#define OPOVER(_op, _type) inline bool operator _op (const _type &t) const
// }}}
// conversion {{{
inline int toInt(string s) { int v; istringstream sin(s); sin>>v; return v; }
template<class T> inline string toString(T x) { ostringstream sout; sout<<x; return sout.str(); }
// }}}
// array and STL {{{
#define ARRSIZE(a) ( sizeof(a) / sizeof(a[0]) )
#define ZERO(a, v) ( assert(v == 0 || v == -1), memset(a, v, sizeof(a)) )
#define F first
#define S second
#define MP(a, b) make_pair(a, b)
#define SIZE(a) ((LL)a.size())
#define PB(e) push_back(e)
#define SORT(v) sort((v).begin(), (v).end())
#define RSORT(v) sort((v).rbegin(), (v).rend())
#define ALL(a) (a).begin(), (a).end()
#define RALL(a) (a).rbegin(), (a).rend()
#define EACH(c, it) for(typeof((c).begin()) it=(c).begin(); it!=(c).end(); ++it)
#define REACH(c, it) for(typeof((c).rbegin()) it=(c).rbegin(); it!=(c).rend(); ++it)
#define EXIST(s, e) ((s).find(e) != (s).end())
// }}}
// bit manipulation {{{
// singed integers are not for bitwise operations, specifically arithmetic shifts ('>>', and maybe not good for '<<' too)
#define IS_UNSIGNED(n) (!numeric_limits<typeof(n)>::is_signed)
#define BIT(n) (assert(IS_UNSIGNED(n)), assert(n < 64), (1ULL << (n)))
#define BITOF(n, m) (assert(IS_UNSIGNED(n)), assert(m < 64), ((ULL)(n) >> (m) & 1))
inline int BITS_COUNT(ULL b) { int c = 0; while(b != 0) { c += (b & 1); b >>= 1; } return c; }
inline int MSB(ULL b) { int c = 0; while(b != 0) { ++c; b >>= 1; } return c-1; }
inline int MAKE_MASK(ULL upper, ULL lower) { assert(lower < 64 && upper < 64 && lower <= upper); return (BIT(upper) - 1) ^ (BIT(lower) - 1); }
// }}}
// for readable code {{{
#define EVEN(n) (n % 2 == 0)
#define ODD(n) (!EVEN(n))
// }}}
// debug {{{
#define arrsz(a) ( sizeof(a) / sizeof(a[0]) )
#define dprt(fmt, ...) if (opt_debug) { fprintf(stderr, fmt, ##__VA_ARGS__); }
#define darr(a) if (opt_debug) { copy( (a), (a) + arrsz(a), ostream_iterator<int>(cerr, " ") ); cerr << endl; }
#define darr_range(a, f, t) if (opt_debug) { copy( (a) + (f), (a) + (t), ostream_iterator<int>(cerr, " ") ); cerr << endl; }
#define dvec(v) if (opt_debug) { copy( ALL(v), ostream_iterator<int>(cerr, " ") ); cerr << endl; }
#define darr2(a) if (opt_debug) { FOR(__i, 0, (arrsz(a))){ darr( (a)[__i] ); } }
#define dvec2(v) if (opt_debug) { FOR(__i, 0, v.size()){ dvec( (v)[__i] ); } }
#define WAIT() if (opt_debug) { string _wait_; cerr << "(hit return to continue)" << endl; getline(cin, _wait_); }
#define dump(x) if (opt_debug) { cerr << " [L" << __LINE__ << "] " << #x << " = " << (x) << endl; }
#define dumpf() if (opt_debug) { cerr << __PRETTY_FUNCTION__ << endl; }
#define dumpv(x) if (opt_debug) { cerr << " [L:" << __LINE__ << "] " << #x << " = "; REP(q, (x).size()) cerr << (x)[q] << " "; cerr << endl; }
#define where() if (opt_debug) { cerr << __FILE__ << ": " << __PRETTY_FUNCTION__ << " [L: " << __LINE__ << "]" << endl; }
#define show_bits(b, s) if(opt_debug) { REP(i, s) { cerr << BITOF(b, s-1-i); if(i%4 == 3) cerr << ' '; } cerr << endl; }
template<typename T1, typename T2> ostream& operator<<(ostream& s, const pair<T1, T2>& d) {return s << "(" << d.first << ", " << d.second << ")";}
template<typename T> ostream& operator<<(ostream& s, const complex<T>& d) {return s << "(" << d.real() << ", " << d.imag() << ")";}
// }}}
// }}}
// time {{{
inline double now(){ struct timeval tv; gettimeofday(&tv, NULL); return (static_cast<double>(tv.tv_sec) + static_cast<double>(tv.tv_usec) * 1e-6); }
// }}}
// string manipulation {{{
inline VS split(string s, char delimiter) { VS v; string t; REP(i, s.length()) { if(s[i] == delimiter) v.PB(t), t = ""; else t += s[i]; } v.PB(t); return v; }
inline string join(VS s, string j) { string t; REP(i, s.size()) { t += s[i] + j; } return t; }
// }}}
// geometry {{{
#define Y real()
#define X imag()
// }}}
// 2 dimentional array {{{
P dydx4[4] = { P(-1, 0), P(0, 1), P(1, 0), P(0, -1) };
P dydx8[8] = { P(-1, 0), P(0, 1), P(1, 0), P(0, -1), P(-1, 1), P(1, 1), P(1, -1), P(-1, -1) };
int g_height, g_width;
bool in_field(P p) {
	return (0 <= p.Y && p.Y < g_height) && (0 <= p.X && p.X < g_width);
}
// }}}
// }}}
bool opt_debug = false;

int main(int argc, char** argv) {
	std::ios_base::sync_with_stdio(false);
	// set options {{{
	int __c;
	while ( (__c = getopt(argc, argv, "d")) != -1 ) {
		switch (__c) {
			case 'd':
				opt_debug = true;
				break;
			default:
				abort();
		}
	}
	// }}}

	VI mountains(10);
	REP (i, 10) {
		cin >> mountains[i];
	}
	RSORT(mountains);
	REP (i, 3) {
		cout << mountains[i] << endl;
	}

	return 0;
}

// vim: foldmethod=marker

C++: #include<stdio.h>
#include<stdlib.h>

int i,j,a[12];

int comp(const void *p,const void *q){
	return *(int *)q-*(int *)p;
}

int main(){
	scanf("%d",&a[0]);
	for(i=1;i<10;i++)scanf("\n%d",&a[i]);
	
	qsort(a,10,sizeof(int),comp);
	
	printf("%d\n",a[0]);
	printf("%d\n",a[1]);
	printf("%d",a[2]);
	
	return 0;
}

C++: #include<iostream>

using namespace std;

int main(){
    int a[10];
    for(int i=0;i<10;i++)cin>>a[i];
    
    int x=-1,y=-1,z=-1;
    for(int i=0;i<10;i++){
        if(a[i]>x){
            z=y;
            y=x;
            x=a[i];
        }else if(a[i]>y){
            z=y;
            y=a[i];
        }else if(a[i]>z){
            z=a[i];
        }
    }
    cout<<x<<endl<<y<<endl<<z<<endl;
    
    return 0;
}