I Love T code chef solution in C

Read sentences until user enters 0
for each sentence, if the first character in each word in the given sentence is vowel, append T and if it is not vowel replace that character by T. 
Also only first character in each word only must be capital letter.

Sample Input:
love apples
apples are gOOOd for HelatHH
0

Sample Output:
Tove Tapples
Tapples Tare Toood Tor Telathh



#include<stdio.h>
int isvowel(char ch)
{
    if(ch >='A' && ch <= 'Z')
        ch=ch+32;
    if(ch == 'a' ||ch == 'e'||ch == 'i'||ch == 'o'||ch == 'u')
        return 1;
    else
        return 0;
}

int main()
{
    char st[1000001];
    scanf("\n%[^\n]\n",st);
    while(st[0] != '0')
    {
        int i;
        for(i=0;st[i]!='\0';i++)
        {
        if(st[i] >= 'A' && st[i] <= 'Z')
                st[i]=st[i]+32;
        if(i == 0|| (st[i-1] == ' ' && st[i] != ' '))
        {
         
            if(isvowel(st[i]))
                printf("T%c",st[i]);
            else
                printf("T");
        }
        else
            printf("%c",st[i]);
        }
        printf("\n");
        scanf("\n%[^\n]\n",st);
    }
    return 0;
 
}