[Solved] I cant make my code to run and i dont know what is wrong [closed]

by


M is uninitialized!
Read M before creating the array a or, make a big enough to contains all possible input sizes and use M to limit the access to a. The latter this is quite common in competitive programming: create a static array big enough and then use only a portion of it based on other information, like M in this case.

Anyway, the error would be easily spotted enabling compiler warnings Wall -Wextra:
Here is what gcc, clang and icc complains about. 

 gcc   -Wall -Wextra -g -O3 -Wshadow  test.c
test.c: In function ‘main’:
test.c:7:1: warning: ‘M’ is used uninitialized in this function [-Wuninitialized]
 int N, M, a[M], i, j, fake;

             ^~~

 clang   -Wall -Wextra -g -O3 -Wshadow  test.c
test.c:7:13: warning: variable 'M' is uninitialized when used here
      [-Wuninitialized]
int N, M, a[M], i, j, fake;

           ^
test.c:7:9: note: initialize the variable 'M' to silence this warning
int N, M, a[M], i, j, fake;
            ^
         = 0
1 warning generated.

 icc   -Wall -Wextra -g -O3 -Wshadow  test.c
test.c(7): warning #592: variable "M" is used before its value is set
  int N, M, a[M], i, j, fake;

solved I cant make my code to run and i dont know what is wrong [closed]