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<iostream>
#include<cstdio>
#include<vector>
#include<queue>
#include<map>
#include<unordered_map>
#include<stack>
#include<string>
#include<algorithm>
#include<functional>
#include<cstring>
#include<utility>
#include<bits/stdc++.h>
#include<math.h>
using namespace std;

/**** Type Define ****/

typedef long long ll;
typedef pair<ll, ll> P;
typedef pair<ll, P> Q;

/**** Const List   ****/

const ll INF = 1LL << 60;
const ll mod = 1000000007;
const ll dx[4] = {1, 0, -1, 0};
const ll dy[4] = {0, -1, 0, 1};

/**** General Functions ****/

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

ll extgcd(ll a, ll b, ll& x, ll& y) {
  if (b == 0) {
    x = 1, y = 0; return a;
  }
  ll q = a/b, g = extgcd(b, a - q*b, x, y);
  ll z = x - q * y;
  x = y;
  y = z;
  return g;
}

ll invmod (ll a, ll m) { // a^-1 mod m
  ll x, y;
  extgcd(a, m, x, y);
  x %= m;
  if (x < 0) x += m;
  return x;
}

ll nCk(ll n, ll k, ll mod) {
  ll ans = 1;
  for (ll i = n, j = 1; j <= k; i--, j++) ans = (((ans * i) % mod) * invmod(j, mod)) % mod;
  return ans;
}

ll lmin(ll a, ll b) { return a > b ? b : a; };

ll lmax(ll a, ll b) { return a > b ? a : b; };

ll lsum(ll a, ll b) { return a + b; };

/**** Zip ****/

template <typename T>
class Zip {
  vector<T> d;
  bool flag;
public:
  Zip() {
    flag = false;
  }
  void add(T x) {
    d.push_back(x);
    flag = true;
  }
  ll getNum(T x) { // T need to have operator < !!
    if (flag) {
      sort(d.begin(), d.end());
      d.erase(unique(d.begin(), d.end()), d.end());
      flag = false;
    }
    return lower_bound(d.begin(), d.end(), x) - d.begin();
  }
  ll size() {
    if (flag) {
      sort(d.begin(), d.end());
      d.erase(unique(d.begin(), d.end()), d.end());
      flag = false;
    }
    return (ll)d.size();
  }
};

/**** Union Find ****/

class UnionFind {
  vector<ll> par, rank; // par > 0: number, par < 0: -par
public:
  void init(ll n) {
    par.resize(n, 1); rank.resize(n, 0);
  }
  ll getSize(ll x) {
    return par[find(x)];
  }
  ll find(ll x) {
    if (par[x] > 0) return x;
    return -(par[x] = -find(-par[x]));
  }
  void merge(ll x, ll y) {
    x = find(x);
    y = find(y);
    if (x == y) return;
    if (rank[x] < rank[y]) {
      par[y] += par[x];
      par[x] = -y;
    } else {
      par[x] += par[y];
      par[y] = -x;
      if (rank[x] == rank[y]) rank[x]++;
    }
  }
  bool isSame(ll x, ll y) {
    return find(x) == find(y);
  }
};

/**** Segment Tree ****/

template <typename T>
class SegmentTree {
  ll n;
  vector<T> node;
  function<T(T, T)> fun, fun2;
  bool customChange;
  T outValue, initValue;
public:
  void init(ll num, function<T(T, T)> resultFunction, T init, T out, function<T(T, T)> changeFunction = NULL) {
    // changeFunction: (input, beforevalue) => newvalue
    fun = resultFunction;
    fun2 = changeFunction;
    customChange = changeFunction != NULL;
    n = 1;
    while (n < num) n *= 2;
    node.resize(2 * n - 1, init);
    outValue = out;
    initValue = init;
  }
  void valueChange(ll num, T value) {
    num += n-1;
    if (customChange) node[num] = fun2(value, node[num]);
    else node[num] = value;
    while (num > 0) num = (num - 1) / 2, node[num] = fun(node[num * 2 + 1], node[num * 2 + 2]);
  }
  T rangeQuery(ll a, ll b, ll l = 0, ll r = -1, ll k = 0) { // [a, b)
    if (r == -1) r = n;
    if (a <= l && r <= b) return node[k];
    if (b <= l || r <= a) return outValue;
    ll mid = (l + r) / 2;
    return fun(rangeQuery(a, b, l, mid, 2*k+1), rangeQuery(a, b, mid, r, 2*k+2));
  }
};

/**** LIS ****/
ll lis(ll* a, ll n, ll* dp) {
  fill(dp, dp + n, INF);//INFを代入
  for (ll i = 0; i < n; i++) *lower_bound(dp, dp + n, a[i]) = a[i];
  return (ll)(lower_bound(dp, dp + n, INF) - dp);
}


/**** main function ****/
vector<ll> s;
vector<ll> copi;
ll n,r,p,c;
int main(){
  while(1){
    cin>>n>>r;
    if(n==0&&r==0)break;
    s.clear();
    for(int i=0;i<n;i++){
      s.push_back(n-i);
    }
    for(int i=0;i<r;i++){
      cin>>p>>c;
      for(int j=p-1;j<p-1+c;j++){
        copi.push_back(s[j]);
      }
      s.erase(s.begin()+p-1,s.begin()+p-1+c);
      for(int j=copi.size()-1;j>=0;j--){
        s.insert(s.begin(),copi[j]);
      }
      copi.clear();
    }
      cout<<s[0]<<endl;
  }

}

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

using namespace std;

int top_search(int,int,int,int *);
int main(){
	int n,r,c,p;
	int cnt=0;
	int top[51];
	while(1){
		cin>>n>>r;
		if(n==0&&r==0)
			break;
		int *hanahuda=new int[n+1];

		for (int i = n-1; i>=0 ; i--)
			hanahuda[i]=n-i;

		for(int i=0;i<r;i++){
			cin>>p>>c;
			top[cnt]=top_search(n,p,c,hanahuda);
		}
		delete[] hanahuda;
		cnt++;
	}
	for(int m=0;m<cnt;m++)
		cout<<top[m]<<endl;
	return 0;
}
int top_search(int n,int p,int c,int *hanahuda){
	int cnt=0;
	for(int k=p-1;k<p+c-1;k++){

		int nokori=hanahuda[k];

		for(int l=p-2;l>=0;l--)
			hanahuda[l+1]=hanahuda[l];


		hanahuda[cnt]=nokori;
		cnt++;
	}

	return *hanahuda;
}

C++: #include <stdio.h>

int main(){

  int n,r,p,c,i,j;
  int score[51];
  int temp[51];

  for(;;){

    scanf("%d%d",&n,&r);
    if(n==0&&r==0){
      break;
    }

    for(i=1;i<=n;i++){
      score[i]=i;
      temp[i]=i;
    }

    for(i=1;i<=r;i++){
      scanf("%d%d",&p,&c);

      for(j=n-p+1;j>n-p+1-c;j--){
	score[j+p-1]=score[j];
      }
      for(j=n;j>=n-p+1;j--){
	score[j-c]=temp[j];
      }

    }

    printf("%d\n",score[n]);
  }
  return 0;

}

C++: #include<cstdio>
#include<cstdlib>
#include<cstring>
#include<cmath>
#include<climits>
#include<iostream>
#include<algorithm>
#include<stack>
#include<queue>
#include<vector>
#include<list>
#include<map>
#include<set>
using namespace std;
int x[100];
int y[100];
int card [100];
int n,r;
int ans[1000];
int counter;
bool input(){
    for(int i=0;i<100;i++){
    x[i]=0;
    y[i]=0;
    }
    cin >>n>>r;
    for(int i=0;i<r;i++){
    cin>>x[i]>>y[i];
    }
  if(n==0){
    return false;
    }
    else{
     return true;
    }
}
void solve(){
    for(int i=0;i<100;i++){
        card[i]=i+1;
    }
    for(int i=0;i<r;i++){
        for(int k=0;k<y[i];k++){
            int a=card[x[i]+y[i]-2];
            for(int j=x[i]+y[i]-1;j>0;j--){
                card[j]=card[j-1];
            }
            card[0]=a;
       
        }
    }
    cout<<n-card[0]+1<<endl;
  //  ans[counter]=n-card[0];
    counter+=1;
}
    
    
    
int main (){
counter=0;
    while(input()){
    solve();
    }
return 0;
}

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(n);
    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(c);
      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;
}