小弟刚学c语言，不知哪里错

#include <stdio.h>
int len_of_dates(int year,int month,int day);
int len_of_month(int year,int month);
int len_of_year(int year);

int main(){
int year,month,day,s;
scanf("%d,%d,%d",&year,&month,&day);
s= len_of_dates(year,month,day);
printf("%d",s);
}

int len_of_dates(int year,int month,int day){
int n,total;
for(n=1,total=0;n<month;n++)
total+=len_of_month(year,month);
total+=day;
return total;
}

int len_of_month(int year,int month){
int monthday = 31;
if (month==2)
if (len_of_year(year)){
monthday=29;
}else{
monthday=28;
}
if(month==4||month==6||month==9||month==11){
monthday=30;
}
return monthday;
}

int len_of_year(int year){
if((year%4==0&&year%100!=0)||(year%400==0)){
return 1;
}else{
return 0;
}
}

你怎么不把错误报告