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>
using namespace std;
#define rep(i,n) for(long long int i=0;i<n;++i)
typedef long long int ll;

int main(){

    while(1){
        int n,m;
        cin >>n >> m;
        if(n==0&&m==0){
            break;
        }
        vector<vector<int>> a(m);

        for(int i=0;i<n;i++){
            int d,v;
            cin >> d >> v;
            d--;
            a[d].push_back(v);
        }
        int ans=0;
        for(int i=0;i<m;i++){
            sort(a[i].begin(),a[i].end());
            ans+=a[i].back();
        }
        cout << ans << endl;
    }

    return 0;
}

C++: #include <bits/stdc++.h>
using namespace std;
#define rep(i,n) for (int (i)=(0);(i)<(int)(n);++(i))
using ll = long long;
using P = pair<int, int>;
using namespace std;

template<class T> void vin(vector<T>& v, int n) {
    v.resize(n);
    for (int i = 0; i < n; ++i) {
        cin >> v[i];
    }
}

int main() {
    int N, M;
    while (cin >> N >> M and N and M) {
        vector<int> dv[102];
        rep(i, N) {
            int d, v;
            cin >> d >> v;
            dv[d].push_back(v);
        }
        rep(i, M+1) {
            sort(dv[i].rbegin(), dv[i].rend());
        }
        int ans = 0;
        for (int d=1; d<=M; ++d) {
            ans += dv[d][0];
        }
        cout << ans << endl;
    }
    return 0;
}

C++: #include <bits/stdc++.h>
using namespace std;
int main(){
  while (1){
    int N, M;
    cin >> N >> M;
    if (N == 0 && M == 0){
      break;
    }
    vector<int> mx(M, 0);
    for (int i = 0; i < N; i++){
      int d, v;
      cin >> d >> v;
      d--;
      mx[d] = max(mx[d], v);
    }
    int ans = 0;
    for (int i = 0; i < M; i++){
      ans += mx[i];
    }
    cout << ans << endl;
  }
}

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

signed main(){
	int n,m;
	while(cin >> n >> m,n){
		int ma[110] = {},ans = 0;
		for(int i = 0;i < n;i++){
			int t,d;
			cin >> t >> d;
			ma[t] = max(ma[t],d);
		}
		for(int i = 1;i <= m;i++) ans += ma[i];
		cout << ans << endl;
	}
}

C++: #include <cstdio>
#include <iostream>
#include <string>
#include <sstream>
#include <stack>
#include <algorithm>
#include <cmath>
#include <queue>
#include <map>
#include <set>
#include <cstdlib>
#include <bitset>
#include <tuple>
#include <assert.h>
#include <deque>
#include <bitset>
#include <iomanip>
#include <limits>
#include <chrono>
#include <random>
#include <array>
#include <unordered_map>
#include <functional>
#include <complex>
#include <numeric>
template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return 1; } return 0; }
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return 1; } return 0; }

constexpr long long MAX = 5100000;
constexpr long long INF = 1LL << 60;
constexpr int inf = 1 << 28;
constexpr long long mod = 1000000007LL;
//constexpr long long mod = 998244353LL;

using namespace std;
typedef unsigned long long ull;
typedef long long ll;

void solve() {
	int n, m; scanf("%d %d", &n, &m); if (n == 0 and m == 0) exit(0);
	vector<int> s(m);
	for (int i = 0; i < n; i++) {
		int d, v; scanf("%d %d", &d, &v);
		d--;
		chmax(s[d], v);
	}
	int sum = 0; for (int i = 0; i < m; i++) sum += s[i];
	printf("%d\n", sum);
}

int main()
{
	/*
	cin.tie(nullptr);
	ios::sync_with_stdio(false);
	*/
	int kkt = 89;
	while (kkt) {
		solve();
	}
	return 0;
}

C++: #include<bits/stdc++.h>
using namespace std;
typedef long long int ll;
typedef pair<ll,ll> mp;
#define inf 1e9


int main(){
	int n,m;
	while(1){
		cin>>n>>m;
		if(n==0)break;
		vector<int> d(n),v(n);
		vector<int> val(m,0);
		for(int i=0;i<n;i++){
			cin>>d[i]>>v[i];
			val[d[i]-1] = max(val[d[i]-1] , v[i]);
		}
		int sum = 0;
		for(int i=0;i<m;i++)sum+= val[i];
		cout<<sum<<endl;

	}
	return 0;
}

C++: #include<bits/stdc++.h>
using namespace std;
#define ALL(x) x.begin(),x.end()
#define rep(i,n) for(int i=0;i<(n);i++)
#define debug(v) cout<<#v<<":";for(auto x:v){cout<<x<<' ';}cout<<endl;
#define mod 1000000007
using ll=long long;
const int INF=1000000000;
const ll LINF=1001002003004005006ll;
int dx[]={1,0,-1,0},dy[]={0,1,0,-1};
ll gcd(ll a,ll b){return b?gcd(b,a%b):a;}
template<class T>bool chmax(T &a,const T &b){if(a<b){a=b;return true;}return false;}
template<class T>bool chmin(T &a,const T &b){if(b<a){a=b;return true;}return false;}
 
struct IOSetup{
    IOSetup(){
        cin.tie(0);
        ios::sync_with_stdio(0);
        cout<<fixed<<setprecision(12);
    }
} iosetup;
 
template<typename T1,typename T2>
ostream &operator<<(ostream &os,const pair<T1,T2>&p){
    os<<p.first<<" "<<p.second;
    return os;
}
 
template<typename T>
ostream &operator<<(ostream &os,const vector<T>&v){
    for(int i=0;i<(int)v.size();i++) os<<v[i]<<(i+1==(int)v.size()?"":" ");
    return os;
}

template<typename T1,typename T2>
istream &operator>>(istream &is,pair<T1,T2>&p){
    is>>p.first>>p.second;
    return is;
}

template<typename T>
istream &operator>>(istream &is,vector<T>&v){
    for(T &x:v)is>>x;
    return is;
}


signed main(){
    int n,m;
    while(cin>>n>>m,n*m){
        vector<int> v(m,0);
        rep(i,n){
            int a,b;cin>>a>>b;
            a--;
            chmax(v[a],b);
        }
        ll res=0;
        rep(i,m)res+=v[i];
        cout<<res<<endl;
    }
    
    return 0;
}