PCK2016-yo-10.cpp

#include<bits/stdc++.h>
using namespace std;

#define int long long
#define rep(i,n) for(int i=0;i<(n);i++)
#define pb push_back
#define all(v) (v).begin(),(v).end()
typedef vector<int>vint;
typedef pair<int,int>pint;
typedef vector<pint>vpint;
#define fi first
#define se second
template<typename A,typename B>inline void chmin(A &a,B b){if(a>b)a=b;}
template<typename A,typename B>inline void chmax(A &a,B b){if(a<b)a=b;}

const int INF=1001001001001001001ll;

int N,M;
int dp[1001][3001];

int v[3000],h[3000];
int t[1000],s[1000];

int accv[3001];
signed main(){
    cin>>N>>M;
    rep(i,N)cin>>v[i]>>h[i],accv[i+1]=accv[i]+v[i];
    rep(i,M)cin>>t[i]>>s[i];

    fill_n(*dp,1001*3001,-INF);
    dp[0][0]=0;

    for(int i=0;i<M;i++){
        for(int j=0;j<=N;j++){
            if(accv[j]>t[i])break;
            if(j){
                chmax(dp[i+1][j],dp[i][j-1]+h[j-1]);
            }
            if(j>1)chmax(dp[i+1][j],dp[i+1][j-1]+h[j-1]+abs(h[j-2]-h[j-1]));
        }
        for(int j=0;j<=N;j++)chmax(dp[i+1][j],dp[i][j]);
        for(int j=0;j<=N;j++){
            if(dp[i+1][j]<s[i])dp[i+1][j]=-INF;
        }

    }

    for(int i=0;i<=N;i++){
        if(dp[M][i]!=-INF){
            cout<<t[M-1]-accv[i]<<endl;
            return 0;
        }
    }

    cout<<-1<<endl;
    return 0;
}