为什么程序中输入不了a，只能输入b。很简单的内容。

#include<stdio.h>
int multifly(int x,int y);
void main()
{
    int a,b,c,i;
    printf("please enter the value of b:\n");
    scanf("b=%d",&b);
    printf("please enter the value of a:\n");
    scanf("a=%d",&a);
    if(b<=0&&a<=0)
    {
        printf("sorry!you are wrong!\n");
    }
    else{

    for(i=1;i<=a;i++)
    {
        c=multifly(a,b)*c;
    }
    printf("c=%d\n",c);
}
}
int multifly(int x,int y)
{
    long int z;
    z=x*y;
    retur