Codeforces 508C Anya and Ghosts

Anya and GhostsTime limit:2000MS Memory Limit:262144KB 64bit IO Format:%i64d &%i6 4u SubmitStatusPracticecodeforces 508C

Description

Anya loves to watch horror movies. In the best traditions of horror, she'll be visited By  m  ghosts tonight. Anya have lots of candles prepared for the visits, each candle can produce light for Exactly  t  seconds. It takes the girl one second to light one candle. More formally, Anya can spend one second to light one candle, then this candle burns for Exactly  t  seconds and then goes out and can no. longer be used.

For each of the m Ghosts Anya knows the time at which it comes:the i-th visit would happen C5>w_{i seconds after midnight, all wiam is distinct. Each visit lasts exactly one second.}

What's the minimum number of candles Anya should use so this during each visit in least R Candles are bu Rning? Anya can start to light a candle at any time this is an integer number of seconds from midnight, possibly, at the time before Midnight. That's means, she can start to light a candle integer number of seconds before midnight or integer number of seconds AF ter a midnight, or in other words with any integer moment of time.

Input

The first line contains three integers m, t, R (1≤ m, t, r ≤300), representing the number of ghosts to visit Anya, the duration of a candle ' s burning and the minimum number of candles that should burn during each visit.

The next line contains m space-separated numbers w_{i (1≤ i ≤ m, 1≤ wi ≤300), the i-th of them repesents at what second after the Midni Ght the i-th ghost would come. All wi' s is distinct, they follow in the strictly increasing order.}

Output

If It is possible to make at least R Candles burn during all visit, then print the minimum number of cand Les that Anya needs to light for that.

If is impossible, print -1.

Sample Input

Input

1 8 3
10

Output

3

Input

2 10 1
5 8

Output

1

Input

1 1 3
10

Output

-1

Hint

Anya can start lighting a candle in the same second with ghost visit. But this candle isn ' t counted as burning at the this visit.

It takes exactly one second to light up a candle and only after the second this candle is considered burning; It means if Anya starts lighting candle at moment x, candle are buring from second X + 1 to second X + t inclusively.

In the first sample test three candles is enough. For example, Anya can start lighting them in the 3-rd, 5-th and 7-th seconds after the midnight.

The second sample test one candle is enough. For example, Anya can start lighting it one second before the midnight.

In the third sample test the answer are-1, since during each second at most one candle can burn but Anya needs three Candles to light up the the-the-moment when the ghost comes.

1#include <stdio.h>2#include <string.h>3 4 intMain ()5 {6     intM,t,r;7     intw[305];8     intvis[1005],lig[1005];9     inti,j,flg,s,k;Ten      while(SCANF (" %d%d%d", &m,&t,&r)! =EOF) One     { Aflg=1; s=0; -memset (Lig,0,sizeof(Lig)); -memset (Vis,0,sizeof(Vis)); the          for(i=1; i<=m;i++) -         { -scanf"%d",&w[i]); -         } +         if(t<R) -         { +flg=0; A         } at         Else -         { -s=R; -              for(i=w[1]-1; i>=0&& i>=w[1]-r;i--) -vis[i]=1; -              for(i=1; i<=r;i++) in             { -                  for(j=w[1];j<=w[1]+t-i;j++) to                 { +lig[j]++; -                 } the             } *              for(i=2; i<=m;i++) $             {Panax Notoginseng                 if(flg==0) -                      Break; the                 if(lig[w[i]]>=R) +                     Continue; A                 intww=r-Lig[w[i]]; the                  for(j=w[i]-1; j>=w[i]-ww;j--) +                 { -                     if(vis[j]==1) $                     { $flg=0; Break; -                     } -vis[j]=1; thes++; -                 }Wuyi                  for(k=1; k<=ww;k++) the                 { -                      for(j=w[i];j<=w[i]+t-k;j++) Wu                     { -lig[j]++; About                     } $                 } -             } -         } -         if(flg==0) Aprintf"-1\n"); +         Else theprintf"%d\n", s); -     } $     return 0; the } the  the  the  -  in  the  the             /*For (i=0;i<=20;i++) About printf ("%d", vis[i]); the printf ("\ n"); the For (i=0;i<=20;i++) the printf ("%d", Lig[i]); + printf ("\ n");*/

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Codeforces 508C Anya and Ghosts