Вылетает, когда ввожу последний символ

#include "stdafx.h"
#include <stdio.h>
#include <conio.h>
#include <Windows.h>
 
#define N 6
 
struct Student
{
    char lastName[25];
    int marks[3];
};
 
int getMarksSum(Student student)
{
    return student.marks[0] + student.marks[1] + student.marks[2];
}
 
void sortAndPrint(Student students[])
{
    
    Student tmp;
 
    for (int i = N - 1; i >= 0; i--)
    {
        for (int j = 0; j < i; j++)
        {
        
            if (getMarksSum(students[j]) > getMarksSum(students[j + 1]))
            {
                tmp = students[j];
                students[j] = students[j + 1];
                students[j + 1] = tmp;
            }
        }
    }
    for (int i = 0; i < N; i++)
    {
        printf("%s %d %d %d sum = %d\n", students[i].lastName, students[i].marks[0], students[i].marks[1], students[i].marks[2], getMarksSum(students[i]));
    }
}
 
 
int main()
{
 
    Student students[N];
 
    for (int i = 0; i < N; i++)
    {
        printf("Input the last name[%d]: ", i + 1);
        gets_s(students[i].lastName);
 
        printf("Input his mark[1]: ");
        scanf_s("%d", &students[i].marks[0]);
        printf("Input his mark[2]: ");
        scanf_s("%d", &students[i].marks[1]);
        printf("Input his mark[3]: ");
        scanf_s("%d", &students[i].marks[2]);
 
        getchar();
    }
 
    printf("\n");
    sortAndPrint(students);
    
}

gets_s(students[i].lastName,25);