Codeforces Round #398 (Div. 2) B. The Queue

#include<bits/stdc++.h>

using namespace std;

#define X first
#define Y second
#define eps  1e-2
#define gcd __gcd
#define pb push_back
#define PI acos(-1.0)
#define lowbit(x) (x)&(-x)
#define bug printf("!!!!!\n");
#define mem(x,y) memset(x,y,sizeof(x))

typedef long long LL;
typedef long double LD;
typedef pair<int,int> pii;
typedef unsigned long long uLL;

const int maxn = 1e5+2;
const int INF  = 1<<30;
const int mod  = 1e9+7;

#define int long long

int ts,tf,t,n;
int a[maxn];

void solve(){
    scanf("%lld%lld%lld%lld",&ts,&tf,&t,&n);
    for(int i=1;i<=n;i++) scanf("%lld",&a[i]);
    int res1=1e15,res2=1e15,R=ts;
    for(int i=1;i<=n;i++){
        if(a[i]-1+t>tf) continue;
        if(a[i]-1>=R){
            res1=0;res2=R;
        }else{
            if(res1>R-a[i]+1){
                res1=R-a[i]+1;
                res2=a[i]-1;
            }
        }
        R=max(a[i],R)+t;
    }
    if(R+t<=tf) res2=R;
    cout<<res2<<endl;
    return;
}

int32_t main()
{
//    freopen("in.txt","r",stdin);
//    freopen("out.txt","w",stdout);
//    ios::sync_with_stdio(false);
    int t = 1;
    //scanf("%d",&t);
    while(t--){
    //    printf("Case %d: ",cas++);
        solve();
    }
    return 0;
}