[c-prog] Nested structure segmentation fault ??

[Ahmed Shabana]

#include<stdio.h>
#include<string.h>


struct sub {
        char name[100];
};


struct maiN {
        struct sub *s1;
        int c;
};


int main()
{

        struct maiN s0;
        strcpy(s0.s1->name,"hi man ");



        return 0;

}

It compile so good

but when run get segmentation fault
CAN ANY ONE TOLD ME WHY ??