各位大侠帮我看看这段程序哪里错了

#include<stdio.h>
#include<stdlib.h>

int main()
{
    float principal,rate,interest;
    int days;
    printf("enter loan principal (-1 to end):");
    scanf("%f",&principal);
    while(principal!=-1)
    {
        printf("enter interest rate:");
        scanf("%f",&rate);
        printf("enter term of the loan in days:");
        scanf("%d",&days);                           //这行
        interest=(float)principal*rate*days/365;
        printf("the interest charge is:$%.2f\n",interest);
        printf("enter loan principal (-1 to end):");
        scanf("%f",&principal);
    }
    system("pause");
    return 0;
}