Go: package main

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

func main() {
	io := NewIo()
	defer io.Flush()
	for {
		n, m := io.NextInt(), io.NextInt()
		if n == 0 {
			break
		}
		p := make([][]int, m)
		for i := 0; i < n; i++ {
			d, v := io.NextInt()-1, io.NextInt()
			p[d] = append(p[d], v)
		}
		sum := 0
		for i := 0; i < m; i++ {
			max := 0
			for _, v := range p[i] {
				max = intMax(v, max)
			}
			sum += max
		}
		io.Println(sum)
	}
}

func intMax(a, b int) int {
	if a < b {
		return b
	}
	return a
}

// I/O template
type Io struct {
	reader    *bufio.Reader
	writer    *bufio.Writer
	tokens    []string
	nextToken int
}

func NewIo() *Io {
	return &Io{
		reader: bufio.NewReader(os.Stdin),
		writer: bufio.NewWriter(os.Stdout),
	}
}

func (io *Io) Flush() {
	err := io.writer.Flush()
	if err != nil {
		panic(err)
	}
}

func (io *Io) NextLine() string {
	var buff []byte
	for {
		line, isPrefix, err := io.reader.ReadLine()
		if err != nil {
			panic(err)
		}
		buff = append(buff, line...)
		if !isPrefix {
			break
		}
	}
	return string(buff)
}

func (io *Io) Next() string {
	for io.nextToken >= len(io.tokens) {
		line := io.NextLine()
		io.tokens = strings.Fields(line)
		io.nextToken = 0
	}
	s := io.tokens[io.nextToken]
	io.nextToken++
	return s
}

func (io *Io) NextInt() int {
	i, err := strconv.Atoi(io.Next())
	if err != nil {
		panic(err)
	}
	return i
}

func (io *Io) NextFloat() float64 {
	i, err := strconv.ParseFloat(io.Next(), 64)
	if err != nil {
		panic(err)
	}
	return i
}

func (io *Io) Println(a ...interface{}) {
	fmt.Fprintln(io.writer, a...)
}

func (io *Io) Printf(format string, a ...interface{}) {
	fmt.Fprintf(io.writer, format, a...)
}

func (io *Io) PrintIntSlice(a []int) {
	b := []interface{}{}
	for _, x := range a {
		b = append(b, x)
	}
	io.Println(b...)
}

func (io *Io) PrintStringSlice(a []string) {
	b := []interface{}{}
	for _, x := range a {
		b = append(b, x)
	}
	io.Println(b...)
}

func Log(name string, value interface{}) {
	fmt.Fprintf(os.Stderr, "%s=%+v\n", name, value)
}

func ExampleIo() {
	io := NewIo()
	defer io.Flush()
	a := make([]int, 0, 3)
	a[0], a[1], a[2] = io.NextInt(), io.NextInt(), io.NextInt()
	io.Println(a)
	io.PrintIntSlice(a)
	Log("io", a)
}

C++: #include<bits/stdc++.h>
#define MAX 101
#define inf 1<<29
#define linf (1e16)
#define eps (1e-8)
#define Eps (1e-12)
#define mod 1000000007
#define pi acos(-1.0)
#define phi (1.0+sqrt(5.0))/2.0
#define f first
#define s second
#define mp make_pair
#define pb push_back
#define all(a) (a).begin(),(a).end()
#define pd(a) printf("%.10f\n",(double)(a))
#define pld(a) printf("%.10Lf\n",(ld)(a))
#define FOR(i,a,b) for(int i=(a);i<(b);i++)
#define RFOR(i,a,b) for(int i=(a)-1;(b)<=i;i--)
#define Unique(v) v.erase(unique(all(v)),v.end())
#define equals(a,b) (fabs((a)-(b))<eps)
using namespace std;
typedef long double ld;
typedef long long ll;
typedef unsigned long long ull;
typedef pair<int,int> pii;
typedef pair<int,double> pid;
typedef pair<double,int> pdi;
typedef pair<double,double> pdd;
typedef vector<int> vi;
typedef vector<pii> vpi;

int main()
{
  int n,m,c[MAX];
  while(cin>>n && cin>>m && n){
    fill(c,c+MAX,0);
    FOR(i,0,n){
      int d,v;
      cin>>d>>v;
      c[d]=max(c[d],v);
    }
    int ans = 0;
    FOR(i,1,m+1)ans+=c[i];
    cout<<ans<<endl;
  }
  return 0;
}

C++: #include<iostream>
#include<vector>
#include<algorithm>
#include<map>
#include<cstring>
#include<math.h>
#include<bitset>
#include<queue>
#include<set>
#include<iomanip>
#include<math.h>
#include<assert.h>
#include<string>
#include<cstdlib>
#include<cctype>
#include<unordered_map>
// #include<bits/stdc++.h>
using namespace std;
using ll = long long;
using P = pair<int,int>;
constexpr ll INF = 1LL << 40;
const double INFD = 1e100;
const ll mod = 1000000007;
const double PI = 3.1415926535897932384626433832795028841971;
const int dx[4] = {1, 0, -1, 0};
const int dy[4] = {0, 1, 0, -1};
template<class T> inline bool chmin(T& a, T b) {
    if (a > b) {
        a = b;
        return true;
    }
    return false;
}
template<class T> inline bool chmax(T& a, T b) {
    if (a < b) {
        a = b;
        return true;
    }
    return false;
}
// ----------------------------------------------------------------------------

int main(){
  while(1){

  int N,M;
  cin >> N >> M;
  if(N==0 && M==0){
    break;
  }
  vector<int> A(M+1,0);
  for(int i=0; i<N; i++){
    int d,v;
    cin >> d >> v;
    chmax(A[d],v);
  }
  int sum=0;
  for(int i=1; i<=M; i++){
    sum += A[i];
  }
  cout << sum << endl;
}
  return 0;
}

C++: #include <bits/stdc++.h>
using namespace std;
#define REP(i, s, n) for (int i = s; i < n; ++i)
#define rep(i, n) REP(i, 0, n)
#define SORT(c) sort((c).begin(), (c).end())
#define IINF INT_MAX
#define LLINF LLONG_MAX
#define DEBUG true
// sort(a.begin(), a.end(), std::greater<int>());

/*
std::vector<std::string> split(const std::string &input, char delimiter)
{
    std::istringstream stream(input);

    std::string field;
    std::vector<std::string> result;
    while (std::getline(stream, field, delimiter))
    {
        result.push_back(field);
    }
    return result;
}
*/

int main()
{
    int n, m;

    while (cin >> n >> m)
    {
        int mp[101] = {0};
        if (n == 0 && m == 0)
            break;
        int a, b;
        rep(i, n)
        {
            cin >> a >> b;
            mp[a] = max(mp[a], b);
        }
        int ans = 0;
        rep(i, 101)
        {
            if (mp[i] != 0)
                ans += mp[i];
        }
        cout << ans << endl;
    }
    return 0;
}

C++: #include<iostream>
#include<string>
#include<algorithm>
#include<bits/stdc++.h>
#include<vector>
 
using namespace std;


int main(){
	int N,M,ans=0; cin >> N >> M;
	int d[N+10],v[N+10],m[101]={};
	for(int i=0; i<N; i++){
		 cin >> d[i] >> v[i];
		 if(m[d[i]]<=v[i]){
			 m[d[i]]=v[i];
		 }
	}
	for(int i=1; i<=M; i++){
			ans+=m[i];
	}
	cout << ans << endl;
}

C++: #include <bits/stdc++.h>
using namespace std;
#define REP(i, s, n) for (int i = s; i < n; ++i)
#define rep(i, n) REP(i, 0, n)
#define SORT(c) sort((c).begin(), (c).end())
#define IINF INT_MAX
#define LLINF LLONG_MAX
#define DEBUG true
// sort(a.begin(), a.end(), std::greater<int>());

/*
std::vector<std::string> split(const std::string &input, char delimiter)
{
    std::istringstream stream(input);

    std::string field;
    std::vector<std::string> result;
    while (std::getline(stream, field, delimiter))
    {
        result.push_back(field);
    }
    return result;
}
*/

int main()
{
    int n, m;

    while (cin >> n >> m)
    {
        int mp[101] = {0};
        if (n == 0 && m == 0)
            break;
        int a, b;
        rep(i, n)
        {
            cin >> a >> b;
            mp[a] = max(mp[a], b);
        }
        int ans = 0;
        rep(i, 101)
        {
            if (mp[i] != 0)
                ans += mp[i];
        }
        cout << ans << endl;
    }
    return 0;
}

C++: #include "bits/stdc++.h"

using namespace std;

using ll = long long;
using ld = long double;
using P = pair<int, int>;
constexpr ld EPS = 1e-12;
constexpr int INF = numeric_limits<int>::max() / 2;
constexpr int MOD = 1e9 + 7;

int main()
{
    cin.tie(0);
    ios::sync_with_stdio(false);

    int n,m;
    while(cin>>n>>m, n || m){
        vector<vector<int>> p(m+1);
        for(int i=0;i<n;i++){
            int d,v;cin>>d>>v;
            p[d].push_back(v);
        }
        int res=0;
        for(int i=1;i<=m;i++){
            sort(p[i].rbegin(),p[i].rend());
            res += p[i][0];
        }
        cout<<res<<endl;
    }
}

C++: #include<bits/stdc++.h>
using namespace std;
int main(){
  int n,m;
  while(cin>>n>>m,n&&m){
    int cnt[111]={};
    int ans=0;
    for(int i=0;i<n;i++){
      int d,v;
      cin>>d>>v;
      cnt[d]=max(cnt[d],v);
    }
    for(int i=1;i<=m;i++)ans+=cnt[i];
    cout<<ans<<endl;
  }
  return 0;
}