#include <bits/stdc++.h>
#define N 200006
#define mid ((l+r)>>1)
#define ls i<<1
#define rs i<<1|1
#define inf 1e18
#define in l==r
#define in2 x<=l&&r<=y
using namespace std;
map<int,int>g;
int n,k,x,tot,d[N],b[N],ll[N],rr[N],q[N],f[N<<2];long long s[N<<2],a[N];
void down(int i,int l,int r)
{
	if(f[i]){
		f[i]=0;s[i]=inf;
		if(l!=r)f[ls]=f[rs]=1;
	}
}
void build(int i,int l,int r)
{
	if(in){s[i]=-q[l];return;}
	build(ls,l,mid);build(rs,mid+1,r);s[i]=min(s[ls],s[rs]);
}
void del(int i,int l,int r,int x,int y)
{
	down(i,l,r);if(in2){f[i]=1;return;}
	if(x<=mid)del(ls,l,mid,x,y);if(y>mid)del(rs,mid+1,r,x,y);
	down(ls,l,mid);down(rs,mid+1,r);s[i]=min(s[ls],s[rs]);
}
long long query(int i,int l,int r,int x,int y)
{
	down(i,l,r);if(in2)return s[i];
	long long tmp=inf;if(x<=mid)tmp=query(ls,l,mid,x,y);
	if(y>mid)tmp=min(tmp,query(rs,mid+1,r,x,y));return tmp;
}
void change(int i,int l,int r,int x,long long y)
{
	down(i,l,r);if(in){s[i]=min(s[i],y-q[l]);return;}
	if(x<=mid)change(ls,l,mid,x,y);else change(rs,mid+1,r,x,y);
	down(ls,l,mid);down(rs,mid+1,r);s[i]=min(s[ls],s[rs]);
}
long long find(int i,int l,int r)
{
	down(i,l,r);if(in)return s[i]+q[l];
	return min(find(ls,l,mid),find(rs,mid+1,r));
}
int main()
{
	scanf("%d%d",&n,&k);
	for(int i=1;i<=n;i++){
		scanf("%d%d",&x,&b[i]);
		if(b[i]==1&&x*2>k)return puts("-1"),0;
		a[i]=a[i-1]+1LL*x;if(b[i]==2)continue;
		ll[i]=-2LL*a[i-1]%k;ll[i]+=ll[i]<0?k:0;
		rr[i]=-2LL*a[i]%k;rr[i]+=rr[i]<0?k:0;
		d[i]=ll[i];d[n+i]=rr[i];
	}
	sort(d+1,d+2*n+1);
	for(int i=1;i<=2*n;i++)
		if(d[i]!=d[i-1]||i==1)g[d[i]]=++tot,q[tot]=d[i];
	build(1,1,tot);
	for(int i=1;i<=n;i++){
		if(b[i]==2)continue;
		int L=g[ll[i]],R=g[rr[i]];
		if(L>R){
			change(1,1,tot,L,(R+1<L?query(1,1,tot,R+1,L-1):inf)+ll[i]);
			if(R+1<L)del(1,1,tot,R+1,L-1);
		}else{
			change(1,1,tot,L,(1<L?query(1,1,tot,1,L-1):inf)+ll[i]);
			change(1,1,tot,L,(R<tot?query(1,1,tot,R+1,tot):inf)+k+ll[i]);
			if(1<L)del(1,1,tot,1,L-1);
			if(R<tot)del(1,1,tot,R+1,tot);
		}
	}
	printf("%lld",2LL*a[n]+find(1,1,tot));
}