I have a problem with my code

i want to calculate the avergae for every exam, but i have a problem with my code, its return randommlynumbers for average.

could you help me 

#include<stdio.h>
#include<stdlib.h>

struct Student MStudent(struct Student std);
void CalcAvrg(struct Student std);

struct Student{
   int mark[5][5];
   
};

struct Student MStudent(struct Student std){
int i,j;

for(i=0;i<5;i++){
	for(j=0;j<5;j++){
	printf("%d. Student's mark for %d. exam :\n", i+1,j+1);
	scanf("%d", &std.mark[i][j]);	
}   
}

return std;
}
 
void CalcAvrg(struct Student std){
	int i;
	for(i=0;i<5;i++){
		printf("%d. Exam's average is: %d\n", i+1,
		(std.mark[0][i] +std.mark[1][i] + std.mark[2][i]+ std.mark[3][i]+ std.mark[4][i])/5);
	}
}

int main(){
      struct Student dene;
      MStudent(dene);
      CalcAvrg(dene);

	return 0;
}