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 <bits/stdc++.h>
using namespace std;
#define REP(i,n) for(int i=0;i<(int)(n);++i)
#define FOR(i,c) for(__typeof((c).begin())i=(c).begin();i!=(c).end();++i)
#define ALL(c) (c).begin(), (c).end()
#define valid(y,x,h,w) (0<=y&&y<h&&0<=x&&x<w)
#define tpl(...) make_tuple(__VA_ARGS__)
const int INF = 0x3f3f3f3f;
const double EPS = 1e-8;
const double PI = acos(-1);
typedef long long ll;
typedef pair<int,int> pii;
template<class T>bool chmax(T &a, const T &b) { if (a<b) { a=b; return 1; } return 0; }
template<class T>bool chmin(T &a, const T &b) { if (a>b) { a=b; return 1; } return 0; }
template<class T>ostream&operator<<(ostream &o,const vector<T>&t){o<<'[';FOR(i,t){if(i!=t.begin())o<<',';o<<*i;}return o<<']';}
template<class S,class T>ostream&operator<<(ostream &o,const pair<S,T>&t){return o<<'('<<t.first<<','<<t.second<<')';}
template<int N,class Tp>void out(ostream&,const Tp&){}
template<int N,class Tp,class,class ...Ts>void out(ostream &o,const Tp&t){if(N)o<<',';o<<get<N>(t);out<N+1,Tp,Ts...>(o,t);}
template<class ...Ts>ostream&operator<<(ostream&o,const tuple<Ts...>&t){o<<'(';out<0,tuple<Ts...>,Ts...>(o,t);return o<<')';}
template<class T>void output(T *a,int n){REP(i,n){if(i)cout<<',';cout<<a[i];}cout<<endl;}
template<class T>void output(T *a,int n,int m){REP(i,n)output(a[i],m);}
template<class T>void output(T t){if(t<0)t=-t,putchar(45);static int c[20];
int k=0;while(t)c[k++]=t%10,t/=10;for(k||(c[k++]=0);k;putchar(c[--k]^48));}
template<class S,class ...T>void output(S a,T...t){output(a);putchar(' ');output(t...);}
template<class T>bool input(T &t){int n=1,c;for(t=0;!isdigit(c=getchar())&&~c&&c-45;);
if(!~c)return 0;for(c-45&&(n=0,t=c^48);isdigit(c=getchar());t=10*t+c-48);t=n?-t:t;return 1;}
template<class S,class ...T>bool input(S&a,T&...t){input(a);return input(t...);}

struct Cmp{
  bool operator()(const string &a, const string &b) {
    return a.size() != b.size() ? a.size() < b.size() : a < b;
  }
};
int main() {
  int n;
  while(cin >> n) {
    map<string,int,Cmp > mp;
    REP(i,n) {
      string s;
      int x;
      cin >> s >> x;
      mp[s] += x;
    }
    FOR(it, mp) {
      cout << it->first << " " << it->second << endl;
    }
  }
}

C++: #include <map>
#include <cstdio>
#include <string>
#include <vector>
#include <iostream>

using namespace std;

bool cmp(const pair<string, int>& x, const pair<string, int>& y)
{
	if (x.first.size() < y.first.size()){
		return true;
	}
	return x.first < y.first;
}

int main()
{
	map<string, int> m;
	string pn;
	int n, c;

	scanf("%d", &n);
	
	for (int i = 0; i < n; i++){
		cin >> pn >> c;

		if (m.count(pn)) m[pn] += c;
		else m.insert(make_pair(pn, c));
	}

	vector< pair<string, int> > v;

	for (map<string, int>::iterator it = m.begin(); it != m.end(); it++){
		v.push_back(*it);
	}

	sort(v.begin(), v.end(), cmp);

	for (vector< pair<string, int> >::iterator it = v.begin(); it != v.end(); it++){
		cout << it->first << " " << it->second << endl;
	}

	return (0);
}

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


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

    foreach(it, c)
        cout << it->first << " " << it->second << endl;
}