two consecutive fgets seg faults

I am currently trying to read in two strings s and t that will be input to stdio. They will be input on separate lines.

The following code segfaults.

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

int main()
{
    char t[5000000];
    char s[5000000];

    fgets(t,50000,stdin);
    fgets(s,50000,stdin);

    printf("%c",t[1]);


}

However, a single fgets doesn't.

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

int main()
{
    char t[5000000];
    char s[5000000];

    fgets(t,50000,stdin);

    printf("%c",t[1]);

}

Other posts talk about some return and "/n" issues, but I don't understand what the problem is exactly.