def count$\_$participation$\_$ways$($N$,$ M$,$ constraints$)$:

# Create a list to represent participation status of students

participation $=[$False$]*($N $+1)$

# Create a set of pairs of students who don't wish to participate together

disallowed$\_$pairs $=$ set$()$

for a$,$ b in constraints:

disallowed$\_$pairs.add$(($a$,$ b$))$

disallowed$\_$pairs.add$(($b$,$ a$))$

# Function to backtrack and count participation ways

def backtrack$($student$)$:

if student $==$ N $+1$:

return $1$

total$\_$ways $=0$

for i in range$($student$,$ N $+1)$:

if not participation$[$i$]$:

valid $=$ True

for j in range$(1,$ i$)$:

if participation$[$j$]$ and $($j$,$ i$)$ in disallowed$\_$pairs:

valid $=$ False

break

if valid:

participation$[$i$]=$ True

total$\_$ways $+=$ backtrack$($student $+1)$

participation$[$i$]=$ False

return total$\_$ways

# Start backtracking from the first student

ways $=$ backtrack$(1)$

return ways

# Reading input

N$,$ M $=$ map$($int$,$ input$().$split$())$

constraints $=[]$

for $\_$ in range$($M$)$:

a$,$ b $=$ map$($int$,$ input$().$split$())$

constraints.append$(($a$,$ b$))$

# Counting participation ways and printing the result

result $=$ count$\_$participation$\_$ways$($N$,$ M$,$ constraints$)$

print$($result$)$