#include<bits/stdc++.h>
typedef long long ll;
ll gi(){
	ll x=0,f=1;
	char ch=getchar();
	while(!isdigit(ch))f^=ch=='-',ch=getchar();
	while(isdigit(ch))x=x*10+ch-'0',ch=getchar();
	return f?x:-x;
}
ll A[100010],B[100010],L[100010],R[100010],u,up[200010];
#define mid ((l+r)>>1)
ll mn[800010];bool tag[800010];
void upd(int x){mn[x]=1e18;tag[x]=1;}
void down(int x){if(tag[x])upd(x<<1),upd(x<<1|1),tag[x]=0;}
void build(int x,int l,int r){
	mn[x]=-up[r];if(l==r)return;
	build(x<<1,l,mid),build(x<<1|1,mid+1,r);
}
void update(int x,int l,int r,int p,ll d){
	if(l==r){mn[x]=d;return;}
	down(x);
	if(p<=mid)update(x<<1,l,mid,p,d);
	else update(x<<1|1,mid+1,r,p,d);
	mn[x]=std::min(mn[x<<1],mn[x<<1|1]);
}
void update0(int x,int l,int r,int L,int R){
	if(L<=l&&r<=R)return upd(x);
	down(x);
	if(L<=mid)update0(x<<1,l,mid,L,R);
	if(mid<R)update0(x<<1|1,mid+1,r,L,R);
	mn[x]=std::min(mn[x<<1],mn[x<<1|1]);
}
ll query(int x,int l,int r,int L,int R){
	if(L<=l&&r<=R)return mn[x];
	down(x);
	if(L<=mid)
		if(mid<R)return std::min(query(x<<1,l,mid,L,R),query(x<<1|1,mid+1,r,L,R));
		else return query(x<<1,l,mid,L,R);
	else return query(x<<1|1,mid+1,r,L,R);
}
#undef mid
int main(){
#ifdef XZZSB
	freopen("in.in","r",stdin);
	freopen("out.out","w",stdout);
#endif
	int n=gi(),K=gi();
	for(int i=1;i<=n;++i){
		A[i]=gi(),B[i]=gi();
		if(B[i]==1&&A[i]*2>K)return puts("-1"),0;
	}
	for(int i=1;i<=n;++i)A[i]+=A[i-1];
	ll ans=1e18;
	for(int i=1;i<=n;++i)
		if(B[i]==1){
			L[i]=(-2*A[i-1]%K+K)%K,R[i]=(-2*A[i]%K+K)%K;
			up[++u]=L[i],up[++u]=R[i];
		}
	std::sort(up+1,up+u+1);u=std::unique(up+1,up+u+1)-up-1;
	for(int i=1;i<=n;++i)if(B[i]==1)L[i]=std::lower_bound(up+1,up+u+1,L[i])-up;
	for(int i=1;i<=n;++i)if(B[i]==1)R[i]=std::lower_bound(up+1,up+u+1,R[i])-up;
	if(u)build(1,1,u);
	for(int i=1;i<=n;++i)
		if(B[i]==1){
			int l=L[i],r=R[i];
			if(l<=r){
				ll _=1e18;
				_=std::min(_,query(1,1,u,1,l));
				if(r<u)_=std::min(_,K+query(1,1,u,r+1,u));
				update(1,1,u,l,_);
				if(l>1)update0(1,1,u,1,l-1);
				if(r<u)update0(1,1,u,r+1,u);
			}else{
				ll _=1e18;
				_=query(1,1,u,r+1,l);
				update(1,1,u,l,_);
				if(r+1<=l-1)update0(1,1,u,r+1,l-1);
			}
		}
	for(int i=1;i<=u;++i)ans=std::min(ans,query(1,1,u,i,i)+up[i]);
	if(!u)ans=0;
	printf("%lld\n",ans+A[n]*2);
	return 0;
}
