#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <memory.h>
#include <math.h>
#include <assert.h>
#include <queue>
#include <map>
#include <set>
#include <string>
#include <algorithm>
#include <iostream>
#include <functional>
#include <unordered_map>
#include <unordered_set>
#include <list>
#include <bitset>

using namespace std;
typedef pair<int, int> Pi;
typedef long long ll;
#define pii Pi
#define pll PL
#define Fi first
#define Se second
#define pb(x) push_back(x)
//#define sz(x) ((int)(x).size())
#define rep(i, n) for(int i=0;i<n;i++)
#define all(x) (x).begin(), (x).end()
typedef tuple<int, int, int> t3;
typedef pair<ll, ll> pll;
typedef long double ldouble;
typedef pair<double, double> pdd;

const double PI = acos(-1);
const double EPS = 1e-9;

const int L = 1 << 30;
const int MX = 1 << 17;

int A[MX], B[MX];
ll up[MX], down[MX], sum[MX];

struct node{
	int l, r, v;
	node(){}
	node(int l, int r, int v):l(l), r(r), v(v){}
} NODES[MX * 60];
int sz = 1;

int& left(int x){ return NODES[x].l; }
int& right(int x){ return NODES[x].r; }
int& value(int x){ return NODES[x].v; }

int new_node(int l, int r, int v){
	NODES[++sz] = node(l, r, v);
	return sz;
}

int mn, mx;
int N, K, ch = 0;

int mn_f(int x, int y){ return min(x, y); }
int mx_f(int x, int y){ return max(x, y); }

void update(int l, int r, int v, int (*f)(int, int), int n, int s = 0, int e = L-1){
	if( l <= s && e <= r ){
		value(n) = f(value(n), v);
	}
	else if( e < l || r < s );
	else{
		int m = (s+e) / 2;
		if( !left(n) ) left(n) = new_node(0, 0, value(n));
		if( !right(n) ) right(n) = new_node(0, 0, value(n));
		update(l, r, v, f, left(n), s, m);
		update(l, r, v, f, right(n), m+1, e);
	}
}

int read(int x, int (*f)(int, int), int n, int s = 0, int e = L-1){
	int m = (s+e) / 2;
	if( s == e ) return value(n);
	else if( x <= m ){
		if( !left(n) ) left(n) = new_node(0, 0, value(n));
		return f(value(n), read(x, f, left(n), s, m));
	}
	else{
		if( !right(n) ) right(n) = new_node(0, 0, value(n));
		return f(value(n), read(x, f, right(n), m+1, e));
	}
}

ll fit(ll a, int u){
	return (a+u-1) / u * u;
}

void find_update_mx(ll s, ll e, int v){
	s++;
	s %= K, e %= K;
	if( e >= s ) update(s, e, v, mx_f, mx);
	else update(0, e, v, mx_f, mx), update(s, K, v, mx_f, mx);
}

int find_value_mx(ll val){
	return read(val%K, mx_f, mx);
}

void find_update_mn(ll s, ll e, int v){
	s++;
	s %= K, e %= K;
	if( e >= s ) update(s, e, v, mn_f, mn);
	else update(0, e, v, mn_f, mn), update(s, K, v, mn_f, mn);
}

int find_value_mn(ll val){
	return read(val%K, mn_f, mn);
}

int main()
{
	scanf("%d%d", &N, &K);
	
	mn = new_node(0, 0, N+1);
	mx = new_node(0, 0, 0);

	for(int i = 1; i <= N; i++){
		scanf("%d%d", A+i, B+i); A[i] *= 2;
		sum[i] = sum[i-1] + A[i];
		if( B[i] == 1 && A[i] > K ) return !printf("-1\n");
		if( B[i] == 2 ) ch = 1;
	}

	for(int i = 1; i <= N; i++){
		int d = find_value_mx(sum[i]);
		
		if( d == 0 ) up[i] = sum[i];
		else up[i] = up[d] + fit(sum[i] - sum[d], K);

		if( B[i] == 1 ) find_update_mx(sum[i-1], sum[i], i);
	}
	for(int i = N; i >= 1; i--){
		int d = find_value_mn(sum[i-1]);
		
		if( d == N+1 ) down[i] = sum[N] - sum[i-1];
		else down[i] = down[d] + fit(sum[d] - sum[i-1], K);
		
		if( B[i] == 1 ) find_update_mn(sum[i-1], sum[i], i);
	}
	ll ans = 1e18;
	for(int i = 0; i <= N; i++){
		ans = min(ans, up[i] + down[i+1]);
	}
	printf("%lld\n", ans);
}


Measured memory_bytes: 67840