请问三天打鱼两天晒网的代码错在哪里，无法运行但没有显示错误

#include<stdio.h>
#define YEAR 1990
#define MONTH 1
int mian()
{
    int year,month,day,i=0;
    int y=0,m=0,len=0;
    printf("please input year month and day\n");
    while(!i)
    {
        scanf("%d%d%d",&year,&month,&day);
        if(year<YEAR||month>12||month<1||day>31||day<1)
        printf("data error,please input the right numbers\n");
        else i=1;
    }
    month=month-1;
    while(month>=1)
    {
        switch(month)
    {
        case 1:
        case 3:
        case 5:
        case 7:
        case 8:
        case 10:
        case 12:m=31;break;
        case 4:
        case 6:
        case 9:
        case 11:m=30;break;
        case 2:
        {
            if((year%4==0&&year%100!=0)||(year%400==0))
            m=29;
            else m=28;
        }
        month--;
        len=m+len;
    }
    }
    if(year>YEAR)
    y=(year-YEAR)*365;
    else y=0;
    len=len+y+day;
    if(len%5==0||(len+1)%5==0)
    printf("he is having a rest.\n");
    else printf("he is working.\n");
    return 0;
}

#include<stdio.h>
#define YEAR 1990
#define MONTH 1
int main() //main不是mian
{
    int year,month,day,i=0;
    int y=0,m=0,len=0;
    printf("please input year month and day\n");
    while(!i)
    {
        scanf("%d%d%d",&year,&month,&day);
        if(year<YEAR||month>12||month<1||day>31||day<1)
        printf("data error,please input the right numbers\n");
        else i=1;
    }
    month=month-1;
    while(month>=1)
    {
                month--; //改！
        switch(month + 1) //改
    {
        case 1:
        case 3:
        case 5:
        case 7:
        case 8:
        case 10:
        case 12:m=31;break;
        case 4:
        case 6:
        case 9:
        case 11:m=30;break;
        case 2:
        {
            if((year%4==0&&year%100!=0)||(year%400==0))
            m=29;
            else m=28;
        }

        len=m+len;
    }
    }
    if(year>YEAR)
    y=(year-YEAR)*365;
    else y=0;
    len=len+y+day;
    if(len%5==0||(len+1)%5==0)
    printf("he is having a rest.\n");
    else printf("he is working.\n");
    return 0;
}

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