Prog#151: display from nth line to mth line

C Programming
#1 
/*
display from nth line to mth line
Program#151
*/
#include<stdio.h>
main()
{
int i,j,b[50],n,m;
char a[50];
for(i=0;(a[i]=getchar())!='$';i++);
a[i]='\0';
j=0;
b[j++]=0;
for(i=0;a[i];i++);
{
if(a[i]=='\n')
b[j++]=i+1;
}
b[j]=-1;
scanf("%d %d", &n, &m);
j=b[m];
for(i=b[n-1];i<j; i++);
printf("%c",a[i]);
}