Go: package main

import "fmt"

func main() {
	var n, r int
	fmt.Scan(&n, &r)
	for n != 0 || r != 0 {
		arr := make([]int, n)
		for i := range arr {
			arr[i] = len(arr) - i
		}

		for i := 0; i < r; i++ {
			var p, c int
			fmt.Scan(&p, &c)
			mid, top, last := arr[:p-1], arr[p-1:p-1+c], arr[p-1+c:]
			arr = append(append(append([]int{}, top...), mid...), last...)
		}
		fmt.Println(arr[0])
		fmt.Scan(&n, &r)
	}
}

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

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;
}

// std::vector Declaration
template<typename T>
vector<T> make_v(size_t a) { return vector<T>(a); }
template<typename T, typename... Ts>
auto make_v(size_t a, Ts... ts) {
    return vector<decltype(make_v<T>(ts...))>(a, make_v<T>(ts...));
}

// std::vector Declaration and Initialization
template<typename T>
vector<T> make_vector(size_t a, T x) { return vector<T>(a, x); }
template<typename T, typename U, typename... Ts>
auto make_vector(size_t a, U b, Ts... ts) {
    return vector<decltype(make_vector<T>(b,ts...))>(a, make_vector<T>(b, ts...));
}

// std::vector Input
template<typename T>
istream& operator>>(istream& is, vector<T>& v) {
    for (auto &e : v) is >> e;
    return is;
}

// std::vector Debug
template<typename T>
ostream& operator<<(ostream& os, const vector<T>& v) {
    os << "[";
    bool a = 1;
    for (auto e : v) {
        os << (a ? "" : " ");
        os << e;
        a = 0;
    }
    os << "]";
    return os;
}

// std::array Debug
template<typename T, size_t n>
ostream& operator<<(ostream& os, const array<T, n>& v) {
    os << "[";
    bool a = 1;
    for (auto e : v) {
        os << (a ? "" : " ");
        os << e;
        a = 0;
    }
    os << "]";
    return os;
}

// std::deque Debug
template<typename T>
ostream& operator<<(ostream& os, const deque<T>& d) {
    os << "[";
    bool a = 1;
    for (auto e : d) {
        os << (a ? "" : " ");
        os << e;
        a = 0;
    }
    os << "]";
    return os;
}

// std::pair Debug
template<typename T, typename U>
ostream& operator<<(ostream& os, const pair<T, U>& p) {
    os << "(" << p.first << " " << p.second << ")";
    return os;
}

// std::set Debug
template<typename T>
ostream& operator<<(ostream& os, const set<T>& st) {
    os << "{";
    bool a = 1;
    for (auto e : st) {
        os << (a ? "" : " ");
        os << e;
        a = 0;
    }
    os << "}";
    return os;
}

// std::multiset Debug
template<typename T>
ostream& operator<<(ostream& os, const multiset<T>& st) {
    os << "{";
    bool a = 1;
    for (auto e : st) {
        os << (a ? "" : " ");
        os << e;
        a = 0;
    }
    os << "}";
    return os;
}

// std::map Debug
template<typename T, typename U>
ostream& operator<<(ostream& os, const map<T, U>& mp) {
    os << "{";
    bool a = 1;
    for (auto e : mp) {
        os << (a ? "" : " ");
        os << e.first << ":" << e.second;
        a = 0;
    }
    os << "}";
    return os;
}

// std::tuple Debug
template<int N, class Tuple>
void out(ostream& os, const Tuple& t){}
template<int N, class Tuple, class H, class ...Ts>
void out(ostream& os, const Tuple& t) {
    if (N) os << " ";
    os << get<N>(t);
    out<N+1,Tuple,Ts...>(os, t);
}
template<class ...Ts>
ostream& operator<<(ostream& os, const tuple<Ts...>& t) {
    os << "(";
    out<0,tuple<Ts...>,Ts...>(os, t);
    os << ")";
    return os;
}

// Debug
#define DUMP(x) cerr<<#x<<" = "<<(x)<<endl

// Weighted edge
template<typename T>
struct edge {
    int src, to;
    T cost;

    edge() {}
    edge(int to, T cost) : src(-1), to(to), cost(cost) {}
    edge(int src, int to, T cost) : src(src), to(to), cost(cost) {}

    friend ostream& operator<<(ostream& os, const edge& e) {
        return os << "(" << e.src << "->" << e.to << ":" << e.cost << ")";
    }
};

using LL = long long;

#define fs first
#define sc second

const LL MOD = 1e9+7;

void shuffle(auto& s, int p, int c) {
    auto buff = s;
    for (int i = 0; i < p-1; ++i) {
        buff[i+c] = s[i];
    }
    for (int i = 0; i < c; ++i) {
        buff[i] = s[i+p-1];
    }
    s = buff;
};

int main()
{
    cin.tie(0);
    ios::sync_with_stdio(false);
    cout << fixed << setprecision(10);

    while (true) {
        int n, r; cin >> n >> r;
        if (n == 0 && r == 0) {
            break;
        }

        vector<int> s(n);
        for (int i = 0; i < n; ++i) {
            s[i] = n-i;
        }

        for (int i = 0; i < r; ++i) {
            int p, c; cin >> p >> c;
            shuffle(s, p, c);
        }

        cout << s[0] << endl;
    }

    return 0;
}

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

using namespace std;

int main(){
	int n,r;
	while(cin >> n >> r,n|r){
		vector<int> v;
		for(int i=0;i<n;i++)
			v.push_back(n-i);
		for(int i=0;i<r;i++){
			int p,c;
			cin >> p >> c;
			p--;
			vector<int> a;
			for(int j=p;j<p+c;j++)
				a.push_back(v[j]);
			for(int j=0;j<p;j++)
				a.push_back(v[j]);
			for(int j=p+c;j<n;j++)
				a.push_back(v[j]);
			v=a;
		}
		cout << v[0] << endl;
	}
	return 0;
}

C++: #include <iostream>
#define MAX_N 50
using namespace std;


int a[MAX_N];
int n, r, p, c;


void set_deck() {
  for(int i = 0; i < n; ++i) {
    a[i] = n - i;
  }
}


void PRINT() {
  cout << "----------" << endl;
  for(int i = 0; i < n; ++i) {
    cout << a[i] << endl;
  }
  cout << "----------" << endl;
}


void cut() {
  int tmp[MAX_N];

  // 青を避難
  for(int i = 0; i < p - 1; ++i) {
    tmp[i] = a[i];
  }

  // 黄色を配置
  for(int i = 0; i < c; ++i) {
    a[i] = a[p - 1 + i];
  }

  // 青を配置
  for(int i = 0; i < p - 1; ++i) {
    a[c + i] = tmp[i];
  }
}


int main() {
  while(cin >> n >> r && n && r) {
    set_deck();
    //PRINT();
    for(int i = 0; i < r; ++i) {
      cin >> p >> c;
      cut();
      //PRINT();
    }
    cout << a[0] << endl;
  }
  return 0;
}

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

int N, R, p, c;

void show(vector<int> v){
    for (int i = 0; i < N; i++){
        cout << v[i] << " ";
    }
    cout << endl;
}

int main(){
    while (cin >> N >> R && N){
        vector<int> card(N);
        for (int i = 0; i < N; i++){
            card[i] = N - i;
        }
        cout << "初期入力"<< endl;
        show(card);

        for (int i = 0; i < R; i++){
            cin >> p >> c;
            rotate(card.begin(), card.begin()+p-1, card.begin()+p+c-1);
            cout << i+1 << "回目のrotate" << endl;
            show(card);
        }
        cout << card[0] << endl;
    }
}

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

#define REP(i,n) for(int i=0;i<(n);i++)

using namespace std;

int main(){
    int n, r;
    vector<int> vc;
    while(cin >> n >> r){
        if(n == 0 && r == 0) break;
        vc.clear();
        REP(i,n){
            vc.insert(vc.begin(),i+1);
        }
        int p, c;
        REP(i,r){
            cin >> p >> c;
            REP(j, c){
                int tmp = vc[p+c-2];
                vc.erase(vc.begin()+p+c-2);
                vc.insert(vc.begin(), tmp);
            }
        }
        cout << vc.front() << endl;
    }
    return 0;
}

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

using namespace std;

vector<int> Deck;

void shuffle(int p, int c) {
  vector<int> tmp = Deck;
  for(int i=0; i<Deck.size(); i++) {
    if(i<=c) {
      Deck[i] = tmp[p+i-1]; // -1不要?
    }
    else if(i) {
      Deck[i] = tmp[i-c];
    }
  }
}

int main() {
  int n, r;

  while(cin>>n>>r && n>0) {
    Deck.clear();
    for(int i=0; i<n; i++) {
      Deck.push_back(n-i);
    }
    for(int i=0; i<r; i++) {
      int p, c;
      cin>>p>>c;
      shuffle(p, c);
    }
    cout<<Deck[0]<<endl;
  }
}