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 <stdio.h>

int main(){
    int n,r,i,j,p,c,a[51],b[51];
    while(1){
        scanf("%d %d",&n,&r);
        if (n==0&&r==0) break;
        for (i=1;i<=n;i++) {
            a[i]=i; //a[i]????????????i??????????????????????????????????????????
        }
        for (i=0;i<r;i++) {
            scanf("%d %d",&p,&c);
            for (j=1;j<=c;j++) {
                b[j]=a[j];
                a[j]=a[j+p-1];
            }
            if (p-1>c) {
                for (j=c+1;j<p;j++) {
                    b[j]=a[j];
                }
            }
            for (j=1;j<p;j++) {
                a[j+c]=b[j];
            }
        }
        
    }
    return 0;
}

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

int main(){
  int n, r, p, c, l[50];

  while(cin >> n >> r, n | r){
    for(int i=0;i<n;i++)
      l[i]=n-i;
    for(int i=0;i<r;i++){
      cin >> p >> c;
      rotate(l,l+p-1,l+p+c-1);
    }
    cout<<l[0]<<endl;
  }

  return 0;
}

C++: #include <algorithm>
#include <bitset>
#include <complex>
#include <deque>
#include <iostream>
#include <istream>
#include <iterator>
#include <map>
#include <queue>
#include <set>
#include <stack>
#include <string>
#include <vector>
#include <tuple>
#include <iomanip>
#include <climits>
#include <fstream>
#include <random>
using namespace std;

typedef long long ll;
typedef unsigned long long ull;
#define rep(i, n) for(int i = 0; i < (n); i++)
#define revrep(i, n) for(int i = (n)-1; i >= 0; i--)
#define pb push_back
#define f first
#define s second
#define chmin(x, y) x = min(x, y);
#define chmax(x, y) x = max(x, y);
#define sz(x) ((int)(x).size())

//const ll INFL = LLONG_MAX;//10^18 = 2^60
const ll INFL = 1LL<<60;
//const int INF = INT_MAX;
const int INF = 1 << 30;//10^9
const ll MOD = 1000000007;
//const ll MOD = 998244353;
double EPS = 1e-10;

vector<ll> dy = {0, 1, 0, -1, 1, 1, -1, -1, 0};
vector<ll> dx = {1, 0, -1, 0, 1, -1, 1, -1, 0};

void pres(double A){printf("%.12lf\n", A);}
void BinarySay(ll x, ll y = 60){rep(i, y) cout << (x>>(y-1-i) & 1); cout << endl;}
ll cnt_bit(ll x){return __builtin_popcountll(x);}

ll pow_long(ll x, ll k){
  ll res = 1;
  while(k > 0){
    if(k % 2) res *= x;
    x *= x; k /= 2;
  }
  return res;
}

ll pow_mod(ll x, ll k){
  x %= MOD;
  ll res = 1;
  while(k > 0){
    if(k % 2){
      res *= x; res %= MOD;
    }
    x *= x; x %= MOD;
    k /= 2;
  }
  return res;
}

void solve(){
  while(true){
    int n, r;
    cin >> n >> r;
    if(n == 0 && r == 0) return;
    vector<int> now(n), ne(n);
    rep(i, n) now[i] = n - i;
    rep(_, r){
      int p, c;
      cin >> p >> c;
      rep(i, c){
        ne[i] = now[i+p-1];
      }
      rep(i, p-1){
        ne[i+c] = now[i];
      }
      rep(i, n-p-c+1){
        ne[i+p+c-1] = now[i+p+c-1];
      }
      now = ne;
    }
    cout << now[0] << endl;
  }
}

int main(){
  ios_base::sync_with_stdio(0);
  cin.tie(0), cout.tie(0);
  solve();
}

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

#define rep(i,j) REP((i), 0, (j))
#define REP(i,j,k) for(int i=(j);(i)<(k);++i)
#define between(a,x,b) ((a)<=(x)&&(x)<=(b))
using namespace std;

int main(){
  int n, r;
  while(scanf("%d%d", &n, &r) && n && r){
    vector<int>a(1000);
    rep(i, n) a[i] = n-i;
    int p, c;
    //    rep(i, n) printf("%d ", a[i]); puts("");
    while(r--){
      scanf("%d%d", &p, &c);p--;
      vector<int>tmp(1000);
      REP(i, p, p + c) tmp[i-p] = a[i];
      for(int i = p; i > 0; --i) a[i] = a[i-c];
      rep(i, c) a[i] = tmp[i];
      //      rep(i, n) printf("%d ", a[i]); puts("");
      //      rep(i, c) printf("%d ", tmp[i]); puts("");
    }
    //    rep(i, n) printf("%d ", a[i]); puts("");
    printf("%d\n", a[0]);
  }
  return 0;
}

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

using namespace std;

int main(){
    int n, r;
    while(cin >> n >> r, n|r){
        vector<int> deck;
        for(int i=n; i>0; --i)deck.push_back(i);
        while(r--){
            int p, c;
            cin >> p >> c;
            --p;
            rotate(deck.begin(), deck.begin() + p, deck.begin() + p + c);
        }
        cout << deck[0] << '\n';
    }
    return 0;
}

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

using namespace std;

#define ll long long
#define vi  vector<int>
#define vvi vector<vi>
#define pi  pair<int,int>
#define mp  make_pair
#define pb  push_back
#define MOD 1e9 + 7
#define PAI  3.1415
#define all(x) (x).begin(),(x).end()
#define chmax(x,y) x = max(x,y)
#define chmin(x,y) x = min(x,y)
#define pr(x) cout << x << endl
#define Endl endl
#define rep(i,n) for(int i = 0 ; i < n; i++)

const int dx[4] = {1,0,-1,0};
const int dy[4] = {0,1,0,-1};
const int ddx[8] = {-1,0,1,-1,1,-1,0,1};
const int ddy[8] = {-1,-1,-1,0,0,1,1,1};
const int inf = 99999999;
const ll linf = 1LL << 62;

ll gcd(ll a,ll b){
  if(a < b)swap(a , b);
  if(a % b == 0) return b;
  else gcd(b, a%b);
}

ll lcm(ll a,ll b){
  if(a < b)swap(a , b);
  return (a/gcd(a , b))*b;
}

struct UnionFind {
  vi par; //par[i] : iの親番号（例）par[3] = 2 : 3の親は2

  UnionFind(int N) : par(N) { //最初は全てが根として初期化
    rep(i,N) par[i] = i;
  }

  int root(int x){ //データxが属する木の根を再帰で得る : root(x) = {xの木の根}
    if(par[x] == x)return x;
    return par[x] = root(par[x]);
  }

  void unite(int x, int y){ //xとyの木を併合
    int rx = root(x); //xの根をrx
    int ry = root(y); //yの根をry
    if(rx == ry)return; //xとyの根が同じ
    par[rx] = ry; //xとyの根が同じでない時、xの根rxをyの根にryにつける。
  }

  bool same(int x, int y){//2つのデータx，yが属する木が同じならtrueを返す
    int rx = root(x);
    int ry = root(y);
    return rx == ry;
  }
};

int main(){

  int n,r;

  while(cin >> n >> r , n){
    string s = "";
    for(int i = n ; i > 0 ; i--) s += '0' + i;

    int p , c;
    rep(i , r){
      string t = "";
      cin >> p >> c;
      int pos = p - 1;

      for(int j = pos ; j < pos + c ; j++)
        t += s[j];

      s.erase(pos , c);
      t += s; s = t;
     }
    cout << s[0] << endl;
  }

  return 0;

}

C++: #include <iostream>
#include <algorithm>
#include <vector>
#include <stack>
#include <queue>
#include <map>
#include <cmath>
#include <string>
#include <sstream>
#include <iomanip>
#include <complex>
using namespace std;

#define ll long long
#define vvi vector< vector<int> >
#define All(X) X.begin(),X.end()
#define FOR(i,a,b) for(int i=(int)(a);i<(int)(b);i++)
#define REP(i,n) for(int i=0;i<(int)(n);i++)
#define pb push_back 
ll gcd(ll a,ll b){return b?gcd(b,a%b):a;}
ll lcm(ll a,ll b){return a/gcd(a,b)*b;}

int main(){
	int n,r;
	int data[100];
	while(1){
		cin >> n >> r;
		if(n==0&&r==0) break;
		REP(i,100) data[i] = n-i+1;
		REP(i,r){
			int p,c;
			cin >> p >> c;
			int newdata[100];
			REP(j,c){
				newdata[j+1] = data[p+j];
			}
			REP(j,p){
				newdata[j+c+1] = data[j+1];
			}
			FOR(j,p+c,n+1){
				newdata[j] = data[j];
			}
			REP(i,100) data[i] = newdata[i];
		}
		cout << data[1] << endl;
	}
}