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

using namespace std;

#pragma GCC optimize("Ofast")

typedef long long lint;

typedef unsigned int uint;

typedef pair<int, int> pii;

typedef pair<lint, lint> pll;

typedef unsigned long long ulint;

#define endl '\n'

#define fst first

#define sed second

#define pb push_back

#define mp make_pair

#define rint register int

#define newline putchar('\n')

#define leave_space putchar(' ')

#define all(x) (x).begin(), (x).end()

#define reveal(x) cerr << #x << " = " << (x) << endl

#define rep(it, f, e) for (rint it = (f); it <= (e); ++it)

#define per(it, f, e) for (rint it = (f); it >= (e); --it)

const lint INF = 1e18;

const int MAXN = 1e5 + 5;

int a[MAXN], b[MAXN], n, k;

struct Segment_tree {

	#define lson tree[root].ls

	#define rson tree[root].rs

	#define stdl (tree[root].sl)

	#define stdr (tree[root].sr)

	#define mid ((stdl + stdr) >> 1)

	struct Node {

		int sl, sr, ls, rs;

		lint val, rval, cover;

		Node () : ls(-1), rs(-1), cover(-1) {} 

	};

	vector<Node> tree;

	inline int new_Node(int l, int r) {

		static int root = 0;

		tree.pb(Node());

		stdl = l, stdr = r;

		tree[root].val = 0;

		tree[root].rval = l;

		return root++;

	}

	inline void update(int root) {

		if (~tree[root].cover) {

			tree[root].val = tree[root].cover;

			tree[root].rval = stdl + tree[root].cover;

		} else {

			tree[root].val = min(tree[lson].val, tree[rson].val);

			tree[root].rval = min(tree[lson].rval, tree[rson].rval);

		}

	}

	inline void pushdown(int root) {

		int L = lson, R = rson;

		if (lson == -1) L = new_Node(stdl, mid);

		if (rson == -1) R = new_Node(mid + 1, stdr);

		lson = L, rson = R;

		/*

			lson = new_Node(stdl, mid); ? RE

		*/

		if (~tree[root].cover) {

			tree[lson].cover = tree[rson].cover = tree[root].cover;

			update(lson), update(rson), tree[root].cover = -1;

		}

	}

	inline void replace(int root, int l, int r, lint p) {

		if (l <= stdl && stdr <= r) {

			tree[root].cover = p;

			update(root);

			return;

		}

		pushdown(root);

		if (l <= mid) replace(lson, l, r, p);

		if (r >= mid + 1) replace(rson, l, r, p);

		update(root);

	}

	inline lint query(int root, int l, int r) {

		if (l <= stdl && stdr <= r) {

			return tree[root].rval;

		}

		pushdown(root);

		lint ret = INF;

		if (l <= mid) ret = min(ret, query(lson, l, r));

		if (r >= mid + 1) ret = min(ret, query(rson, l, r));

		return ret;

	}

	#undef lson

	#undef rson

	#undef stdl

	#undef stdr

	#undef mid

	/*lint tree[10086];

	inline void new_Node(int l, int r) {

		rep (i, l, r) {

			tree[i] = i;

		}

	}

	inline void replace(int root, int l, int r, lint p) {

		rep (i, l, r) { tree[i] = i + p; }

	}

	inline lint query(int root, int l, int r) {

		lint ret = INF;

		rep (i, l, r) { ret = min(ret, tree[i]); }

		return ret;

	}

	inline lint query2(int root, int l, int r) {

		lint ret = INF;

		rep (i, l, r) { ret = min(ret, tree[i] - i); }

		return ret;

	}*/

}	Tree;

inline lint getquery(lint T) {

	return min(Tree.query(0, 0, T) + k - T, Tree.query(0, T, k - 1) - T);

}

int main() {

	ios::sync_with_stdio(false);

	cin.tie(NULL), cout.tie(NULL);

	cin >> n >> k;

	Tree.new_Node(0, k - 1);

	lint ans = 0, res, T = 0;

	rep (i, 1, n) {

		cin >> a[i] >> b[i];

		ans += (a[i] <<= 1);

	}

	rep (i, 1, n) {

		if (b[i] == 1) {

			if (a[i] > k) {

				puts("-1"); return 0;

			}

			lint l = (T + 1) % k;

			lint r = (T + a[i] - 1) % k;

			lint val = getquery(T);

			if (l > r) {

				Tree.replace(0, 0, r, INF);

				Tree.replace(0, l, k - 1, INF);

			} else {

				Tree.replace(0, l, r, INF);

			}

			Tree.replace(0, T, T, val);

			T = (T + a[i]) % k;

		} else {

			T = (T + a[i]) % k;

			Tree.replace(0, T, T, getquery(T));

		}

	}

	res = Tree.tree[0].val;

	cout << (res < INF ? res + ans : -1) << endl;

	return 0;

}

// Faster C++ solution for the same problem (measured speedup: 1.117671392994048x):
#include <bits/stdc++.h>



#define MAXN 100005

#define ls x << 1

#define rs x << 1 | 1

#define INF 0x3f3f3f3f3f3f3f3f



typedef long long lint;



using namespace std;



int n, m, k; 

lint a[MAXN], suma[MAXN], b[MAXN], l[MAXN], r[MAXN], ele[MAXN << 1];

lint f[MAXN << 1];



struct segment {

	int l, r, v;

}t[MAXN << 3];



int read() {

	char c = getchar();

	int x = 0;

	while (!isdigit(c))

		c = getchar();

	while (isdigit(c)) {

		x = (x << 3) + (x << 1) + c - '0';

		c = getchar();

	}

	return x;

}



void build(int l = 1, int r = m, int x = 1) {

	t[x].l = l;

	t[x].r = r;

	t[x].v = 0;

	if (l == r)

		return ;

	int mid = (l + r) >> 1;

	build(l, mid, ls);

	build(mid + 1, r, rs);

}



void pushdown(int x) {

	if (t[x].v) {

		t[ls].v = t[rs].v = t[x].v;

		t[x].v = 0;

	}

}



void modify(int l, int r, int v, int x = 1) {

	if (l > r)

		return ;

	if (l <= t[x].l && t[x].r <= r) {

		t[x].v = v;

		return ;

	}

	pushdown(x);

	int mid = (t[x].l + t[x].r) >> 1;

	if (l <= mid)

		modify(l, r, v, ls);

	if (r > mid)

		modify(l, r, v, rs);

}



int query(int p, int x = 1) {

	if (t[x].l == t[x].r)

		return t[x].v;

	pushdown(x);

	int mid = (t[x].l + t[x].r) >> 1;

	if (p <= mid)

		return query(p, ls);

	return query(p, rs);

}



int dis(int x, int y) {

	return (ele[y] - ele[x] + k) % k;

}



int main() {

	// freopen("s.txt", "r", stdin);

	// freopen("a.out", "w", stdout);

	n = read();

	k = read();

	for (int i = 1; i <= n; ++i) {

		a[i] = read();

		b[i] = read();

		if (b[i] == 1 && a[i] * 2 > k) {

			puts("-1");

			return 0;

		}

		suma[i] = suma[i - 1] + a[i];

	}

	for (int i = 1; i <= n; ++i) {

		if (b[i] == 1) {

			l[i] = (-suma[i - 1] * 2 % k + k) % k;

			r[i] = (-suma[i] * 2 % k + k) % k;

		}

		else {

			l[i] = 0;

			r[i] = k - 1;

		}

		ele[++m] = l[i];

		ele[++m] = r[i];

	}

	sort(ele + 1, ele + m + 1);

	m = unique(ele + 1, ele + m + 1) - ele - 1;

	build();

	for (int i = 1; i <= n; ++i) {

		l[i] = lower_bound(ele + 1, ele + m + 1, l[i]) - ele;

		r[i] = lower_bound(ele + 1, ele + m + 1, r[i]) - ele;

	}

	for (int i = n; i >= 1; --i) {

		int j = query(l[i]);

		if (!j)

			f[i] = 0;

		else 

			f[i] = f[j] + dis(l[i], l[j]);

		// cout << i << " " << f[i] << " " << l[i] << " " << r[i] << endl;

		if (l[i] <= r[i]) {

			modify(1, l[i] - 1, i);

			modify(r[i] + 1, m, i);

		}

		else 

			modify(r[i] + 1, l[i] - 1, i);

	}

	lint ans = f[1];

	for (int i = 1; i <= m; ++i) {

		int j = query(i);

		if (!j)

			ans = 0;

		ans = min(ans, f[j] + dis(i, l[j]));

	}

	printf("%lld\n", ans + suma[n] * 2);

}