I want to know how to find the value of the constant M from the following c and corresponding assembler code. Is there any method to determine M just by analysing the code?

#include<stdio.h>
int main(){
    
    int i=7;
    int a[14];
    
    a[i] = 99;
    
    int b[M];
    b[i] = 88;
 }

Assembly code given

main : 
endr64
pushq %rbp
movq %rsp, %rbp
subq $80, %rsp
movl $7, -80(%rbp)
movl -80(%rbp),