Go: package main

import (
	"bufio"
	"fmt"
	"os"
	"strconv"
)

var scanner = bufio.NewScanner(os.Stdin)

func nextString() string {
	scanner.Scan()
	return scanner.Text()
}

func nextInt() int {
	n, err := strconv.Atoi(nextString())
	if err != nil {
		fmt.Printf("strconv.Atoi failed: %v\n", err)
	}
	return n
}

var infty = 1000000000

type DirectedGraphNodeID int

type DirectedGraphNode struct {
	key         DirectedGraphNodeID
	adjacents   []*DirectedGraphNode
	costs       []int
	distance    int
	predecessor *DirectedGraphNode
}

func newDirectedGraph(nNodes int) *DirectedGraph {
	graph := DirectedGraph{}
	graph.nodes = make([]*DirectedGraphNode, nNodes)
	for i := 0; i < nNodes; i++ {
		node := DirectedGraphNode{}
		node.key = DirectedGraphNodeID(i)
		node.distance = infty
		graph.nodes[i] = &node
	}
	return &graph
}

type DirectedGraph struct {
	nodes []*DirectedGraphNode
}

func (g *DirectedGraph) setAdjacency(i, j DirectedGraphNodeID, cost int) {
	g.nodes[i].adjacents = append(g.nodes[i].adjacents, g.nodes[j])
	g.nodes[i].costs = append(g.nodes[i].costs, cost)
}

func (g *DirectedGraph) print() {
	for i := 0; i < len(g.nodes); i++ {
		node := g.nodes[i]
		key := node.key
		strings := []string{strconv.Itoa(int(key)), strconv.Itoa(node.distance)}
		for j := 0; j < len(node.adjacents); j++ {
			nodeJ := fmt.Sprintf("(%v, %v)", node.adjacents[j].key, node.costs[j])
			strings = append(strings, nodeJ)
		}
		fmt.Printf("%v\n", strings)
	}
}

func (g *DirectedGraph) relaxEdge(l, r *DirectedGraphNode, w int) {
	if r.distance > l.distance+w {
		// fmt.Printf("%v -> %v, %v\n", l.key, r.key, l.distance+w)
		r.distance = l.distance + w
		r.predecessor = l
	}
}

func main() {
	scanner.Split(bufio.ScanWords)

	nNodes := nextInt()
	graph := newDirectedGraph(nNodes)

	for i := 0; i < nNodes; i++ {
		iNode := DirectedGraphNodeID(nextInt())
		nAdjacent := nextInt()
		for j := 0; j < nAdjacent; j++ {
			jNode := DirectedGraphNodeID(nextInt())
			cost := nextInt()
			graph.setAdjacency(iNode, jNode, cost)
		}
	}

	graph.nodes[0].distance = 0
	for iNode := 0; iNode < nNodes; iNode++ {
		for iLeft := 0; iLeft < len(graph.nodes); iLeft++ {
			nodeLeft := graph.nodes[iLeft]
			for iRight := 0; iRight < len(nodeLeft.adjacents); iRight++ {
				nodeRight := nodeLeft.adjacents[iRight]
				cost := nodeLeft.costs[iRight]
				graph.relaxEdge(nodeLeft, nodeRight, cost)
			}
		}
	}

	// graph.print()

	for iNode := 0; iNode < len(graph.nodes); iNode++ {
		node := graph.nodes[iNode]
		fmt.Println(node.key, node.distance)
	}
}

C++: // include
//------------------------------------------
#include <bits/stdc++.h>

using namespace std;

// conversion
//------------------------------------------
inline int toInt(string s) {
    int v;
    istringstream sin(s);
    sin >> v;
    return v;
}
template <class T>
inline string toString(T x) {
    ostringstream sout;
    sout << x;
    return sout.str();
}

// math
//-------------------------------------------
template <class T>
inline T sqr(T x) {
    return x * x;
}

// typedef
//------------------------------------------
typedef vector<int> VI;
typedef vector<VI> VVI;
typedef vector<string> VS;
typedef pair<int, int> PII;
typedef long long LL;

// container util
//------------------------------------------
#define ALL(a) (a).begin(), (a).end()
#define RALL(a) (a).rbegin(), (a).rend()
#define PB push_back
#define MP make_pair
#define SZ(a) int((a).size())
#define EACH(i, c) \
    for (typeof((c).begin()) i = (c).begin(); i != (c).end(); ++i)
#define EXIST(s, e) ((s).find(e) != (s).end())
#define SORT(c) sort((c).begin(), (c).end())

// repetition
//------------------------------------------
#define FOR(i, a, b) for (int i = (a); i < (b); ++i)
#define REP(i, n) FOR(i, 0, n)
#define REPI(itr, ds) for (auto itr = ds.begin(); itr != ds.end(); itr++)

// constant
//--------------------------------------------
const double EPS = 1e-10;
const double PI = acos(-1.0);
const int INF_INT = 2147483647;
const LL INF_LL = 9223372036854775807;

// clear memory
//--------------------------------------------
#define CLR(a) memset((a), 0, sizeof(a))

// vector
//--------------------------------------------
template <typename T>
istream &operator>>(istream &is, vector<T> &vec) {
    for (T &x : vec) is >> x;
    return is;
}

// pair
//--------------------------------------------
template <typename T, typename U>
ostream &operator<<(ostream &os, pair<T, U> &pair_var) {
    os << "(" << pair_var.first << ", " << pair_var.second << ")";
    return os;
}

// vector
//--------------------------------------------
template <typename T>
ostream &operator<<(ostream &os, const vector<T> &vec) {
    os << "{";
    for (int i = 0; i < vec.size(); i++) {
        os << vec[i] << (i + 1 == vec.size() ? "" : ", ");
    }
    os << "}";
    return os;
}

// list
//--------------------------------------------
template <typename T>
ostream &operator<<(ostream &os, const list<T> &lst) {
    os << "{";
    REPI(itr, lst) {
        os << *itr;
        itr++;
        if (itr != lst.end()) os << ", ";
        itr--;
    }
    os << "}";
    return os;
}

// map
//--------------------------------------------
template <typename T, typename U>
ostream &operator<<(ostream &os, map<T, U> &map_var) {
    os << "{";
    REPI(itr, map_var) {
        os << *itr;
        itr++;
        if (itr != map_var.end()) os << ", ";
        itr--;
    }
    os << "}";
    return os;
}

// set
//--------------------------------------------
template <typename T>
ostream &operator<<(ostream &os, set<T> &set_var) {
    os << "{";
    REPI(itr, set_var) {
        os << *itr;
        itr++;
        if (itr != set_var.end()) os << ", ";
        itr--;
    }
    os << "}";
    return os;
}

// dump
//--------------------------------------------
#define DUMPOUT cerr

void dump_func() { DUMPOUT << endl; }
template <class Head, class... Tail>
void dump_func(Head &&head, Tail &&... tail) {
    DUMPOUT << head;
    if (sizeof...(Tail) > 0) {
        DUMPOUT << ", ";
    }
    dump_func(std::move(tail)...);
}
#ifdef DEBUG_
#define DEB
#define dump(...)                                                       \
    DUMPOUT << "  " << string(#__VA_ARGS__) << ": "                     \
            << "[" << to_string(__LINE__) << ":" << __FUNCTION__ << "]" \
            << endl                                                     \
            << "    ",                                                  \
        dump_func(__VA_ARGS__)
#else
#define DEB if (false)
#define dump(...)
#endif

static const int MAX = 100;
static const int INFTY = (1 << 21);
enum Color { WHITE, GRAY, BLACK };

int n, m[MAX][MAX];

void dijkstra() {
    int d[MAX];
    Color c[MAX];
    REP(i, n) {
        d[i] = INFTY;
        c[i] = Color::WHITE;
    }

    d[0] = 0;
    c[0] = Color::GRAY;
    while (true) {
        int minv = INFTY;
        int u = -1;
        REP(i, n) {
            if (minv > d[i] && c[i] != Color::BLACK) {
                u = i;
                minv = d[i];
            }
        }
        if (u == -1) break;
        c[u] = Color::BLACK;
        REP(v, n) {
            if (c[v] != Color::BLACK && m[u][v] != INFTY) {
                if (d[v] > d[u] + m[u][v]) {
                    d[v] = d[u] + m[u][v];
                    c[v] = Color::GRAY;
                }
            }
        }
    }
    REP(i, n) cout << i << " " << (d[i] == INFTY ? -1 : d[i]) << endl;
}

int main(void) {
    cin >> n;
    REP(i, n) REP(j, n) m[i][j] = INFTY;
    REP(i, n) {
        int u, k;
        cin >> u >> k;
        REP(j, k) {
            int v, c;
            cin >> v >> c;
            m[u][v] = c;
        }
    }
    dijkstra();
    return 0;
}