Go: package main

import (
	"fmt"
	"sort"
)

type node struct {
	Key string
	Num int
}

func main() {
	var n int
	fmt.Scan(&n)
	m := make(map[string]int)
	for i := 0; i < n; i++ {
		var s string
		var num int
		fmt.Scan(&s, &num)
		if _, ok := m[s]; !ok {
			m[s] = 0
		}
		m[s] += num
	}
	list := make([]node, 0, len(m))
	for k, v := range m {
		list = append(list, node{Key: k, Num: v})
	}
	sort.Slice(list, func(i, j int) bool {
		if len(list[i].Key) == len(list[j].Key) {
			return list[i].Key < list[j].Key
		} else {
			return len(list[i].Key) < len(list[j].Key)
		}
	})
	for _, v := range list {
		fmt.Println(v.Key, v.Num)
	}
}

C++: #include <cstdio>
#include <cstdlib>
#include <cstring>
#include <cmath>
#include <climits>
#include <cfloat>
#include <ctime>
#include <cassert>
#include <map>
#include <utility>
#include <set>
#include <iostream>
#include <memory>
#include <string>
#include <vector>
#include <algorithm>
#include <functional>
#include <sstream>
#include <complex>
#include <stack>
#include <queue>
#include <numeric>
#include <list>
#include <iomanip>
#include <fstream>
#include <bitset>
   
using namespace std;
   
 
#define rep(i, n) for (int i = 0; i < (int)(n); ++i)
#define foreach(it, c) for (__typeof__((c).begin()) it=(c).begin(); it != (c).end(); ++it)
#define rforeach(it, c) for (__typeof__((c).rbegin()) it=(c).rbegin(); it != (c).rend(); ++it)
#define all(c) (c).begin(), (c).end()
#define rall(c) (c).rbegin(), (c).rend()
#define CL(arr, val) memset(arr, val, sizeof(arr))
#define COPY(dest, src) memcpy(dest, src, sizeof(dest))
#define ten(n) ((long long)(1e##n))
#define bin(n) (1LL << (n))
#define erep(i, n) for (int i = 0; i <= (int)(n); ++i)
#define revrep(i, n) for (int i = (n); i >= 0; --i)
#define pb push_back

template <class T> void chmax(T& a, const T& b) { a = max(a, b); }
template <class T> void chmin(T& a, const T& b) { a = min(a, b); }

template <class T> void uniq(T& c) { sort(c.begin(), c.end()); c.erase(unique(c.begin(), c.end()), c.end()); }
 
template <class T> string to_s(const T& a) { ostringstream os; os << a; return os.str(); }
template <class T> T to_T(const string& s) { istringstream is(s); T res; is >> res; return res; }

template <typename T> void print_container(ostream& os, const T& c) { const char* _s = " "; if (!c.empty()) { __typeof__(c.begin()) last = --c.end(); foreach (it, c) { os << *it; if (it != last) cout << _s; } } }
template <typename T> ostream& operator<<(ostream& os, const vector<T>& c) { print_container(os, c); return os; }
template <typename T> ostream& operator<<(ostream& os, const set<T>& c) { print_container(os, c); return os; }
template <typename T> ostream& operator<<(ostream& os, const multiset<T>& c) { print_container(os, c); return os; }
template <typename T> ostream& operator<<(ostream& os, const deque<T>& c) { print_container(os, c); return os; }
template <typename T, typename U> ostream& operator<<(ostream& os, const map<T, U>& c) { print_container(os, c); return os; }
template <typename T, typename U> ostream& operator<<(ostream& os, const pair<T, U>& p) { os << "(" << p.first << ", " << p.second << ")"; return os; }

template <class T> void print(T a, int n, const string& deli = " ", int br = 1) { for (int i = 0; i < n; ++i) { cout << a[i]; if (i + 1 != n) cout << deli; } while (br--) cout << endl; }
template <class T> void print2d(T a, int w, int h, int width = -1, int br = 1) { for (int i = 0; i < h; ++i) { for (int j = 0; j < w; ++j) {    if (width != -1) cout.width(width); cout << a[i][j] << ' '; } cout << endl; } while (br--) cout << endl; }

template <class T> void input(T& a, int n) { for (int i = 0; i < n; ++i) cin >> a[i]; }
template <class T> void input(T* a, int n) { for (int i = 0; i < n; ++i) cin >> a[i]; }

void fix_pre(int n) { cout.setf(ios::fixed, ios::floatfield); cout.precision(10); }
void fast_io() { cin.tie(0); ios::sync_with_stdio(false); }
#define trace(x) (cout << #x << ": " << (x) << endl)
 
bool in_rect(int x, int y, int w, int h) { return 0 <= x && x < w && 0 <= y && y < h; }

typedef long long ll;
typedef pair<int, int> pint;

// y(v): v>^<  y(^): ^>v<
const int dx[] = { 0, 1, 0, -1 };
const int dy[] = { 1, 0, -1, 0 };

const double PI = acos(-1.0);
#define mp make_pair


bool cmp(const string& a, const string& b)
{
    return a.size() < b.size() || (a.size() == b.size() && a < b);
}
int main()
{
    int n;
    cin >> n;
    map<string, int> c;
    vector<string> pro;
    rep(i, n)
    {
        string s;
        int t;
        cin >> s >> t;
        c[s] += t;
        pro.pb(s);
    }
    uniq(pro);
    sort(all(pro), cmp);

    rep(i, pro.size())
        cout << pro[i] << " " << c[pro[i]] << endl;
}

C++: #include<iostream>
#include<map>
using namespace std;main(){map<string,int>h;map<string,int>::iterator t;int n;string s;for(cin>>n;cin>>s>>n;)h[s]+=n;for(n=0;n++<5;)for(t=h.begin();t!=h.end();t++)if(t->first.size()==n)cout<<t->first<<" "<<t->second<<"\n";}

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

int main(void){

  int n,quantity,tmp,len=1;
  string name;
  map<string, int> product;

  cin >> n;
  
  for(int i = 0; i < n; i++){
    cin >> name >> quantity;
    //テ」ツ?凖」ツ?ァテ」ツ?ォテゥツ?催ィツ、ツ?」ツ?凖」ツつ凝ィツ」ツステ・ツ督?・ツ青催」ツ?古ヲツ慊嘉」ツ?」テ」ツ?淌」ツ?ィテ」ツ??
    if(product.find(name) != product.end()){
      tmp = product.find(name)->second;
      tmp += quantity;
      product.erase(name);
      product.insert(make_pair(name,tmp));
    }else{ //ティツ」ツステ・ツ督?・ツ青催」ツ?古」ツ?ェテ」ツ??」ツ?ィテ」ツ??
      product.insert(make_pair(name,quantity));
    }
  }
  
  while(product.empty() == false){ //テ」ツδ榲」ツδε」ツδ療」ツ?古ァツゥツコテ」ツ?ァテ」ツ?ッテ」ツ?ェテ」ツ??」ツ?ィテ」ツ?催・ツョツ淌ィツ。ツ?
    for (map<string,int>::iterator ite=product.begin(); ite!=product.end(); ite++){
      string str = ite->first;
      int s = str.size();
      if(s == len){
	cout << ite->first << " " << ite->second << endl;
	product.erase(str); //ティツ。ツィテァツ、ツコテ」ツ?療」ツ?淌」ツつ嘉・ツ可甘ゥツ卍、
      }
    }
    len++;
  }
  
  return 0;
}

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

#define reep(i,a,b) for(int i=(a);i<(b);++i)
#define rep(i,n) reep((i),0,(n))
#define ALL(v) (v).begin(),(v).end()
#define PB push_back
#define EPS 1e-8
#define F first
#define S second
#define mkp make_pair

static const double PI=6*asin(0.5);
typedef long long ll;
typedef complex<double> CP;
typedef pair<int,int> pii;
typedef pair<ll,ll> pll;
typedef vector<int> vint;
static const int INF=1<<24;

template <class T>
void initvv(vector<vector<T> > &v,int a,int b, const T  &t = T()){
	v.assign(a,vector<T>(b,t));
}

//v.erase(unique(v.begin(),v.end()),v.end());


map<string,ll> ma;

int main(){
	vector<string> v;
	ll n;
	cin>>n;
	rep(i,n){
		string s;
		ll a;
		cin>>s>>a;
		v.PB(s);
		ma[s]+=a;
	}
	sort(ALL(v));
	v.erase(unique(ALL(v)),v.end());
	vector<pair<int,string> > vv;
	rep(i,v.size()){
		vv.PB(mkp(v[i].size(),v[i]));
	}
	sort(ALL(vv));
	rep(i,vv.size()){
		cout<<vv[i].S<<" "<<ma[vv[i].S]<<endl;
	}
}