C program to merge two arrays?

#include<stdio.h>
int main()
{
int A[50],B[50],C[50],MN=0,M,N,a,b,c;
printf("enter size of 1st array\n");
scanf("%d",&M);
printf("enter size of 2nd array\n");
scanf("%d",&N);
MN=M+N;
printf("enter 1st arrays elements (asending)\n");
for(i=0;i<N,i++)
scanf("%d",&A[i]);
printf("enter 2nd array elements (desending)\n");
for(i=0;i<n;i++)
scanf("%d",&B[i]);
for(a=0;b=N-1;c=0;a<M && b>=0)
{
if[A[a]<=B[b]],c[c+1]=A[a+1];
else
c[c+i]=B(b--);
}
if(a<M)
{
while(a<M),c[c++]=A[a++];
}
else
{
while(b>=0)
c[c++]=B[b--];
}
return o;
}