Please read the following table in Markdown format and then answer the question according to the table. Table cells in one row are seperated by '|', and different rows are seperated by '
'.

Table:
| Date | Course | Distance | Type | Winner |
| --- | --- | --- | --- | --- |
| 13 May | Milan | km (mi) | Team time trial | Renault-Elf |
| 14 May | Parma to Viareggio | km (mi) | Stage with mountain(s) | Giuseppe Saronni ( ITA ) |
| 15 May | Viareggio to Cortona | km (mi) | Plain stage | Michael Wilson ( AUS ) |
| 16 May | Perugia to Assisi | km (mi) | Individual time trial | Bernard Hinault ( FRA ) |
| 17 May | Assisi to Rome | km (mi) | Plain stage | Urs Freuler ( SUI ) |
| 18 May | Rome to Caserta | km (mi) | Plain stage | Urs Freuler ( SUI ) |
| 19 May | Caserta to Castellammare di Stabia | km (mi) | Stage with mountain(s) | Silvano Contini ( ITA ) |
| 20 May | Castellammare di Stabia to Diamante | km (mi) | Plain stage | Francesco Moser ( ITA ) |
| 21 May | Rest day | Rest day | Rest day | Rest day |
| 22 May | Taormina to Agrigento | km (mi) | Stage with mountain(s) | Moreno Argentin ( ITA ) |
| 23 May | Agrigento to Palermo | km (mi) | Stage with mountain(s) | Giuseppe Saronni ( ITA ) |
| 24 May | Cefalù to Messina | km (mi) | Plain stage | Urs Freuler ( SUI ) |
| 25 May | Palmi to Camigliatello Silano | km (mi) | Stage with mountain(s) | Bernard Becaas ( FRA ) |
| 26 May | Rest day | Rest day | Rest day | Rest day |
| 27 May | Cava de' Tirreni to Campitello Matese | km (mi) | Stage with mountain(s) | Bernard Hinault ( FRA ) |
| 28 May | Campitello Matese to Pescara | km (mi) | Stage with mountain(s) | Silvano Contini ( ITA ) |
| 29 May | Pescara to Urbino | km (mi) | Plain stage | Guido Bontempi ( ITA ) |
| 30 May | Urbino to Comacchio | km (mi) | Plain stage | Silvestro Milani ( ITA ) |
| 31 May | Comacchio to San Martino di Castrozza | km (mi) | Stage with mountain(s) | Vicente Belda ( ESP ) |
| 1 June | Fiera di Primiero to Boario Terme | km (mi) | Stage with mountain(s) | Silvano Contini ( ITA ) |
| 2 June | Piancogno to Montecampione | km (mi) | Stage with mountain(s) | Bernard Hinault ( FRA ) |
| 3 June | Boario Terme to Vigevano | km (mi) | Plain stage | Robert Dill-Bundi ( SUI ) |
| 4 June | Vigevano to Cuneo | km (mi) | Plain stage | Francesco Moser ( ITA ) |
| 5 June | Cuneo to Pinerolo | km (mi) | Stage with mountain(s) | Giuseppe Saronni ( ITA ) |
| 6 June | Pinerolo to Turin | km (mi) | Individual time trial | Bernard Hinault ( FRA ) |
| Total | Total | km (mi) | km (mi) | km (mi) |
Question:
What type has rest day as a course and was on 21 may?
Answer:
Rest day