C program to find vowels and consonants in any string

#include<stdio.h>
#include<conio.h>
void main()
{
char a[100];
int i=0,j,v=0,c=0;
puts("Enter the string in lower case");
scanf("%s",a);
while(a[i]!='\0')
{
if(a[i]<'a'||a[i]>'z')
{
j=i;
while(a[j]!='\0')
{
a[j]=a[j+1];
j++;
}
i--;
}
i++;
}
i=0;
while(a[i]!='\0')
{
if(a[i]=='a'||a[i]=='e'||a[i]=='i'||a[i]=='o'||a[i]=='u')
v++;
else c++;
i++;
}
printf("%s",a);
printf("\nNo. of vowels=%d\nNo. of consonants=%d",v,c);
}