Problem:
Score : 100 points

Problem Statement

There are N items, numbered 1, 2, \ldots, N.
For each i (1 \leq i \leq N), Item i has a weight of w_i and a value of v_i.

Taro has decided to choose some of the N items and carry them home in a knapsack.
The capacity of the knapsack is W, which means that the sum of the weights of items taken must be at most W.

Find the maximum possible sum of the values of items that Taro takes home.

Constraints

All values in input are integers.

1 \leq N \leq 100

1 \leq W \leq 10^9

1 \leq w_i \leq W

1 \leq v_i \leq 10^3

Input

Input is given from Standard Input in the following format:

N W
w_1 v_1
w_2 v_2
:
w_N v_N

Output

Print the maximum possible sum of the values of items that Taro takes home.

Sample Input 1

3 8
3 30
4 50
5 60

Sample Output 1

90

Items 1 and 3 should be taken.
Then, the sum of the weights is 3 + 5 = 8, and the sum of the values is 30 + 60 = 90.

Sample Input 2

1 1000000000
1000000000 10

Sample Output 2

10

Sample Input 3

6 15
6 5
5 6
6 4
6 6
3 5
7 2

Sample Output 3

17

Items 2, 4 and 5 should be taken.
Then, the sum of the weights is 5 + 6 + 3 = 14, and the sum of the values is 6 + 6 + 5 = 17.

Solution in C++14 (GCC 5.4.1) (judge verdict: Accepted)

///////////////////////////////////////////////////////////////////////////////

#include <iostream>
#include <iomanip>
#include <vector>
#include <map>
#include <unordered_map>
#include <set>
#include <queue>
#include <deque>
#include <bitset>
#include <algorithm>
#include <cmath>
#include <typeinfo>
#include <numeric>
#include <cassert>
#include <stdio.h>
#include <unistd.h>
#include <string.h>
#include <stdlib.h>

using namespace std;

///////////////////////////////////////////////////////////////////////////////

#define DEBUG 0

#define pb push_back
#define V vector
#define M unordered_map

#define rep(i,n) for(ll i=0LL;i<n;++i)
#define srep(i,s,n) for(ll i=s;i<n;++i)
#define rrep(i,n) for(ll i=n-1LL;i>=0LL;--i)
#define ALL(a) (a).begin(),(a).end()
#define CIN(x) do { \
    assert(!cin.eof()); \
    cin >> x; \
    assert(!cin.fail()); \
} while(0);
#if DEBUG
#define debug_print(...) _debug_print(__VA_ARGS__)
#define debug_printf(...) printf(__VA_ARGS__)
#else // DEBUG
#define debug_print(...)
#define debug_printf(...)
#endif // DEBUG

typedef long long ll;
typedef unsigned long long ull;
typedef tuple<ll, ll> t2;
typedef tuple<ll, ll, ll> t3;
typedef tuple<ll, ll, ll, ll> t4;
typedef tuple<ll, ll, ll, ll, ll> t5;
template <typename T>
using priority_queue_incr = priority_queue<T, V<T>, greater<T>>;

template <typename S, typename T>
T get_m(M<S, T> &m, S k, S default_value)
{
    if (m.find(k) == m.end()) return m[k] = default_value;
    return m[k];
}

struct UnionFind
{
    ull *parent, *count, *rank;

    UnionFind(ull n) {
        parent = new ull[n+1];
        count = new ull[n+1];
        rank = new ull[n+1];
        for (ull i = 0ULL; i < n+1; ++i) {
            parent[i] = i;
            count[i] = 1;
            rank[i] = 0;
        }
    }

    ~UnionFind() {
        delete rank;
        delete count;
        delete parent;
    }

    ull root(ull i) {
        if (parent[i] == i) return i;
        parent[i] = root(parent[i]);
        return parent[i];
    }

    void unite(ull i, ull j) {
        ull rooti = root(i);
        ull rootj = root(j);

        if (rooti == rootj) return;

        if (rank[rootj] < rank[rooti]) {
            parent[i] = parent[j] = parent[rootj] = rooti;
            count[rooti] += count[rootj];
        }
        else {
            parent[i] = parent[j] = parent[rooti] = rootj;
            count[rootj] += count[rooti];
            if (rank[rootj] == rank[rooti]) rank[rootj]++;
        }
    }

    bool same(ull i, ull j) {
        return root(i) == root(j);
    }
};

struct UnionFindM
{
    M<ull, ull> parent, count, rank;

    ull root(ull i) {
        ull parent_i = get_m(parent, i, i);
        if (parent_i == i) return i;
        return parent[i] = root(parent_i);
    }

    void unite(ull i, ull j) {
        ull rooti = root(i);
        ull rootj = root(j);

        if (rooti == rootj) return;

        if (get_m(rank, rootj, 0ULL) < get_m(rank, rooti, 0ULL)) {
            parent[i] = parent[j] = parent[rootj] = rooti;
            count[rooti] = get_m(count, rooti, 1ULL) + get_m(count, rootj, 1ULL);
        }
        else {
            parent[i] = parent[j] = parent[rooti] = rootj;
            count[rootj] = get_m(count, rootj, 1ULL) + get_m(count, rooti, 1ULL);
            if (get_m(rank, rootj, 0ULL) == get_m(rank, rooti, 0ULL)) rank[rootj]++;
        }
    }

    bool same(ull i, ull j) {
        return root(i) == root(j);
    }
};

struct BIT
{
    ll *tree;
    ll size;

    BIT(ll n, ll init) {
        tree = new ll[n+1];
        size = n;
        memset(tree, 0, sizeof(ll) * (n+1));
        this->init(init);
    }

    void init(ll init) {
        rep (i0, size) {
            ll idx = i0 + 1LL;
            while (idx <= size) {
                tree[idx] += init;
                idx += (idx & (-idx));
            }
        }
    }

    // idx is 1 origin
    void add(ll idx, ll x) {
        assert(idx > 0LL);
        while (idx <= size) {
            tree[idx] += x;
            idx += (idx & (-idx));
        }
    }

    // idx is 1 origin
    ll sum(ll idx) {
        assert(idx > 0LL);
        ll ret = 0LL;
        while (idx > 0LL) {
            ret += tree[idx];
            idx -= (idx & (-idx));
        }
        return ret;
    }
};

struct MaxFlow {
    V<ll> links[1005];
    ll capacities[1005][1005];
    ll nodes;

    MaxFlow(ll nodes) {
        // i == 0       --> S
        // i == nodes+1 --> T
        rep (i, nodes+2LL) links[i].clear();
        memset(capacities, 0, sizeof(capacities));
        this->nodes = nodes;
    }

    void add_path(ll a, ll b, ll capacity) {
        links[a].pb(b);
        links[b].pb(a);
        capacities[a][b] = capacity;
        capacities[b][a] = 0LL;
    }

    ll solve(void) {
        deque<V<ll>> q;
        ll ret = 0LL;

        for ( ; ; q.clear()) {

            V<ll> start;
            start.pb(0);
            q.push_front(start);

            bool checked[nodes+2];
            memset(checked, 0, sizeof(checked));

            V<ll> found;

            for ( ; !(q.empty()); ) {
                V<ll> path = q.front(); q.pop_front();
                ll last = path[path.size()-1];

                if (checked[last]) continue;
                if (last == nodes+1) {
                    found = path;
                    break;
                }

                checked[last] = true;
                for (auto next : (links[last])) {
                    if (capacities[last][next] == 0) continue;
                    V<ll> newpath(path);
                    newpath.pb(next);
                    q.push_front(newpath);
                }
            }

            if (found.size() == 0) {
                break;
            }
            else {
                ll flowcount = capacities[found[0]][found[1]];
                rep (i, found.size()-1) {
                    ll src = found[i];
                    ll dst = found[i+1];
                    flowcount = min(flowcount, capacities[src][dst]);
                }
                rep (i, found.size()-1) {
                    ll src = found[i];
                    ll dst = found[i+1];
                    capacities[src][dst] -= flowcount;
                    capacities[dst][src] += flowcount;
                }
                ret += flowcount;
            }
        }

        return ret;
    }
};

template <typename T>
struct SegmentTree {
    T *nodes;
    t2 *ranges;  // [start, end)
    ll nodecount;
    ll itemcount;
    T unit;
    T (*op)(T, T);

    SegmentTree(ll itemcount, T unit, T op(T, T)) {
        ll orig_itemcount = itemcount;
        this->itemcount = 1LL;
        while (this->itemcount < orig_itemcount) this->itemcount *= 2LL;
        nodecount = this->itemcount * 2 - 1;
        nodes = new T[nodecount];
        ranges = new t2[nodecount];
        this->unit = unit;
        this->op = op;

        ll start = 0LL;
        ll end = this->itemcount;
        ll len = this->itemcount;

        rep (i, nodecount) {
            nodes[i] = unit;
            ranges[i] = t2(start, end);
            if (end >= this->itemcount) {
                len /= 2LL;
                start = 0LL;
                end = len;
            }
            else {
                start = end;
                end = start + len;
            }
        }
    }

    void update(ll k, T v) {
        ll idx = k + itemcount - 1LL;
        nodes[idx] = v;
        idx = (idx - 1LL) / 2LL;

        for ( ; idx >= 0; idx = (idx - 1LL) / 2LL) {
            nodes[idx] = op(nodes[idx * 2LL + 1LL],
                            nodes[idx * 2LL + 2LL]);
            if (!idx) break;
        }
    }

    T query(ll start, ll end) const {
        return _query(start, end, 0LL);
    }

    T _query(ll start, ll end, ll idx) const {
        ll rstart = get<0>(ranges[idx]);
        ll rend = get<1>(ranges[idx]);

        if (start <= rstart && rend <= end) {
            return nodes[idx];
        }
        if (rend <= start || end <= rstart) {
            return unit;
        }
        T left = _query(start, end, idx * 2LL + 1LL);
        T right = _query(start, end, idx * 2LL + 2LL);
        return op(left, right);
    }

};

void llin(ll &a)
{
    CIN(a);
}

void llinl1(auto &v, ll count)
{
    for (ll i = 0LL; i < count ; ++i) {
        ll a;
        CIN(a);
        v.push_back(a);
    }
}

void llinl2(auto &v, ll count)
{
    for (ll i = 0LL; i < count ; ++i) {
        ll a, b;
        CIN(a >> b);
        v.push_back(t2(a, b));
    }
}

void llinl3(auto &v, ll count)
{
    for (ll i = 0LL; i < count ; ++i) {
        ll a, b, c;
        CIN(a >> b >> c);
        v.push_back(t3(a, b, c));
    }
}

void llinl4(auto &v, ll count)
{
    for (ll i = 0LL; i < count ; ++i) {
        ll a, b, c, d;
        CIN(a >> b >> c >> d);
        v.push_back(t4(a, b, c, d));
    }
}

void llina(auto &v, ll count)
{
    llinl1(v, count);
}

template <typename T>
T min(const V<T> v)
{
    T ret = v[0];
    for (auto i : v) ret = min(ret, i);
    return ret;
}

template <typename T>
T max(const V<T> v)
{
    T ret = v[0];
    for (auto i : v) ret = max(ret, i);
    return ret;
}

ll absll(ll x)
{
    if (x < 0) return -x;
    return x;
}

ll mod_mlt(ll x, ll y, ll mod)
{
    ll ret = 0LL;
    x %= mod;

    while (y) {
        if (y & 1LL) {
            ret += x;
            ret %= mod;
        }
        y >>= 1;
        x <<= 1;
        x %= mod;
    }

    return ret;
}

// O(log(exp))
ll mod_pow(ll base, ll exp, ll mod)
{
    ll ret = 1LL;

    for ( ; exp; ) {
        if (exp & 1LL) {
            ret *= base;
            ret %= mod;
        }
        base = (base * base) % mod;
        exp >>= 1;
    }

    return ret;
}

// O(log(mod))
ll mod_inv(ll x, ll mod)
{
    // available only when mod is prime
    return mod_pow(x, mod - 2LL, mod);
}

ll gcm(ll x, ll y)
{
    while (y != 0) {
        ll z = x % y;
        x = y;
        y = z;
    }
    return x;
}

template <typename T>
void sort(V<T> &v)
{
    sort(v.begin(), v.end());
}

template <typename T>
void sort_reverse(V<T> &v)
{
    sort(v.begin(), v.end(), greater<T>());
}

void get_divisors(V<ll> &retlist, ll x)
{
    for (ll i = 1LL; i < sqrt(x) + 3LL; ++i) {
        if (x % i == 0LL) {
            retlist.push_back(i);
            retlist.push_back(x / i);
        }
    }
}

void get_factors(V<ll> &retlist, ll x)
{
    for (ll i = 2LL; i < (ll)(sqrt(x)) + 3LL; ++i) {
        while (x % i == 0LL) {
            retlist.pb(i);
            x /= i;
        }
    }
    retlist.pb(x);
}

bool is_prime(ll x)
{
    V<ll> factors, factors2;

    get_factors(factors, x);

    for (auto factor : factors) {
        if (factor > 1) factors2.pb(factor);
    }

    return factors2.size() == 1 && x == factors2[0];
}

template <typename T>
void intersection(const set<T> &a, const set<T> &b,
                  set<T> &result)
{
    set_intersection(ALL(a), ALL(b), inserter(result, result.end()));
}

ull combination(ll x, ll y)
{
    if (y > x / 2LL) y = x - y;

    ull ret = 1LL;
    for (ll i = 0LL; i < y; ++i) {
        ret *= x--;
        ret /= (i + 1LL);
    }

    return ret;
}

ull mod_combination(ll x, ll y, ll mod)
{
    if (y > x / 2LL) y = x - y;

    ll ret = 1;

    for (ll i = 0LL; i < y; ++i) {
        ret = (ret * x--) % mod;
        ret = (ret * mod_inv(i + 1LL, mod)) % mod;
    }

    return ret;
}

void make_linklist(const V<t2> &srclist, V<ll> dstlist[])
{
    for (auto src : srclist) {
        ll a = get<0>(src);
        ll b = get<1>(src);
        dstlist[a].pb(b);
        dstlist[b].pb(a);
    }
}

void make_parental_relation(const V<ll> linklist[], ll root, ll n,
                            ll parent[], V<ll> children[], ll level[])
{
    queue<ll> q;
    bool checked[n+1];

    memset(checked, 0, sizeof(checked));

    q.push(root);
    checked[root] = true;
    parent[root] = root;
    level[root] = 0LL;

    for ( ; !(q.empty()); ) {
        ll now = q.front(); q.pop();
        for (auto next : linklist[now]) {
            if (checked[next]) continue;
            q.push(next);
            checked[next] = true;
            parent[next] = now;
            children[now].pb(next);
            level[next] = level[now] + 1LL;
        }
    }
}

void make_subtree_sizes(const ll child_count[], const ll parents[],
                        ll subtree_sizes[], ll n)
{
    ll remain_count[n+1LL];
    memcpy(remain_count, child_count, sizeof(remain_count));

    queue<ll> q;
    srep (node, 1LL, n+1LL) {
        subtree_sizes[node] = 1LL;
        if (remain_count[node] > 0) continue;
        q.push(node);
    }

    while (!q.empty()) {
        ll node = q.front(); q.pop();
        ll parent = parents[node];
        if (node == parent) continue;
        remain_count[parent]--;
        subtree_sizes[parent] += subtree_sizes[node];
        if (remain_count[parent] == 0LL) q.push(parent);
    }
}

void get_centroids(const V<ll> children[], const ll subtree_sizes[],
                   ll root, ll n, V<ll> &centroids)
{
    queue<ll> q;
    q.push(root);

    while (!q.empty()) {
        ll now = q.front(); q.pop();
        bool is_centroid = true;
        for (auto child : children[now]) {
            q.push(child);
            if (subtree_sizes[child] > n / 2LL) is_centroid = false;
        }
        if (n - subtree_sizes[now] > n / 2LL) is_centroid = false;
        if (is_centroid) centroids.pb(now);
    }

    assert(centroids.size() == 1LL || centroids.size() == 2LL);
}

#define POW_ANCESTOR_MAXSIZE   20

// preprocess for get_common_ancestor()
void make_pow_ancestor(const ll parent[], ll n,
                       ll (*pow_ancestor)[POW_ANCESTOR_MAXSIZE])
{
    rep (i, n) pow_ancestor[i+1][0] = parent[i+1];

    for (int pow2 = 1; pow(2, pow2) <= n; ++pow2) {
        rep (i0, n) {
            int i = i0+1;
            ll prev = pow_ancestor[i][pow2-1];
            pow_ancestor[i][pow2] = pow_ancestor[prev][pow2-1];
        }
    }
}

ll get_common_ancestor(ll n, ll x, ll y,
                       const ll (*pow_ancestor)[POW_ANCESTOR_MAXSIZE],
                       const ll level[])
{
    if (level[x] < level[y]) {
        ll diff = level[y] - level[x];
        for ( ; diff; ) {
            ll bit = diff & -diff;
            y = pow_ancestor[y][(int)log2(bit)];
            diff -= bit;
        }
    }
    else {
        ll diff = level[x] - level[y];
        for ( ; diff; ) {
            ll bit = diff & -diff;
            x = pow_ancestor[x][(int)log2(bit)];
            diff -= bit;
        }
    }

    if (x == y) return x;

    rrep (i, (int)log2(n)+1) {
        if (pow_ancestor[x][i] != pow_ancestor[y][i]) {
            x = pow_ancestor[x][i];
            y = pow_ancestor[y][i];
        }
    }

    return pow_ancestor[x][0];
}

void kmp_init(const string &pattern, ll kmp_next[])
{
    kmp_next[0] = -1LL;

    ll plen = pattern.size();
    ll prefix_end = -1;

    rep (suffix_end, pattern.size()) {
        while (prefix_end >= 0 && pattern[suffix_end] != pattern[prefix_end]) {
            prefix_end = kmp_next[prefix_end];
        }
        kmp_next[suffix_end+1] = ++prefix_end;
    }

    kmp_next[0] = 0LL;
}

// founds ... list of text's idx of match position. start position idx.
void kmp_search(const string &text, const string &pattern, const ll kmp_next[],
                V<ll> &founds)
{
    ll text_size = text.size();
    ll pattern_size = pattern.size();
    ll text_start = 0LL;
    ll pattern_idx = 0LL;

    assert(pattern_size <= text_size);

    for ( ; ; ) {
        if (text_start + pattern_idx >= text_size) break;
        if (pattern_idx >= pattern_size) break;

        if (text[text_start+pattern_idx] == pattern[pattern_idx]) {
            pattern_idx++;
            if (pattern_idx == pattern_size) {
                founds.pb(text_start);
                pattern_idx = kmp_next[pattern_idx];
                text_start += (pattern_size - pattern_idx);
            }
        }

        else {
            text_start += (pattern_idx - kmp_next[pattern_idx]);
            pattern_idx = kmp_next[pattern_idx];
            if (pattern_idx == 0LL && text[text_start] != pattern[0]) {
                text_start++;
            }
        }
    }
}

void _debug_print(auto x)
{
    cout << x << endl;
}

void _debug_print(const t2 &x)
{
    ll x1 = get<0>(x);
    ll x2 = get<1>(x);
    cout << "-- " << x1 << " -- " << x2 << endl;
}

void _debug_print(const t3 &x)
{
    ll x1 = get<0>(x);
    ll x2 = get<1>(x);
    ll x3 = get<2>(x);
    cout << "-- " << x1 << " -- " << x2 << " -- " << x3 << endl;
}

void _debug_print(const t4 &x)
{
    ll x1 = get<0>(x);
    ll x2 = get<1>(x);
    ll x3 = get<2>(x);
    ll x4 = get<3>(x);
    cout << "-- " << x1 << " -- " << x2
        << " -- " << x3 << " -- " << x4 << endl;
}

template <typename T>
void _debug_print(T xarray[], ll n)
{
    rep (i, n) _debug_print(xarray[i]);
}

template <typename T>
void _debug_print(const V<T> &xlist)
{
    for (auto x : xlist) {
        cout << "-- ";
        _debug_print(x);
    }
}

template <typename T>
void _debug_print(const set<T> &xset)
{
    for (auto x : xset) {
        cout << "-- ";
        _debug_print(x);
    }
}

template <typename S, typename T>
void _debug_print(const M<S, T> &xlist)
{
    for (auto x : xlist) {
        S k = x.first;
        T v = x.second;
        cout << "====" << endl;
        cout << "K=";
        _debug_print(k);
        cout << "V=";
        _debug_print(v);
    }
}

int _main();
int main()
{
    cout << setprecision(12);
    return _main();
}

///////////////////////////////////////////////////////////////////////////////

int _main()
{
    ll n; llin(n);
    ll w; llin(w);
    V<t2> wvlist; wvlist.pb(t2(-100LL, -100LL)); llinl2(wvlist, n);

    static ll dp[101][100001];
    rep (i, 101) rep (j, 100001) dp[i][j] = 1e18;
    dp[0][0] = 0LL;

    srep (i, 1LL, n+1) {
        auto wv = wvlist[i];
        ll w = get<0>(wv);
        ll v = get<1>(wv);
        rep (j, 100001) {
            dp[i][j] = min(dp[i][j], dp[i-1][j]);
            if (j+v <= 100000LL) dp[i][j+v] = min(dp[i][j+v], dp[i-1][j] + w);
        }
    }

    ll ans = 0LL;
    rep (i, 100001) if (dp[n][i] <= w) ans = i;
    cout << ans << endl;

    return 0;
}

///////////////////////////////////////////////////////////////////////////////