Basit C kodlama sorusu hatayı nerede yapıyorum ? yardım eder misiniz ?

#include int main(void) { double x1; double x2; double a; double b; double c; double d; printf("Please enter an integer value a:"); a = getchar(); printf("Please enter an integer value b:"); b = getchar(); printf("Please enter an integer value c:"); c = getchar(); if(a==0) { if(b==0) { if(c==0){ printf("every number is solution"); } else{//c != 0 printf("no solution"); } } else//b != 0 { x1 = -c/b; printf("x1 is "); printf(x1); } }else{//a != 0 d = ((b*b)-4*a*c)/4*a*a; if(d