不知道这个代码有啥问题，为啥运行时间超限

#include<stdio.h>
int main()
{
    int chara = 0, num = 0, space = 0, other = 0;
    int ch;
    ch = getchar();
    while (ch != '\n')
    {
        if (ch>= 'A' && ch<= 'Z'||ch>='a'&&ch<='z')
        {
            chara++;
        }
        else if (ch>= '0' && ch<= '9')
        {
            num++;
        }
        else if (ch == ' ')
        {
            space++;
        }
        else
            other++;
        
    }
    printf("%d %d %d %d\n", chara, num, space, other);

    return 0;
}