what does it mean marks_count[total_marks[i]]++;

Question

#include <stdio.h>
int main()
{
int total_marks[] = {86,78,94,69,92,78,64,62,72,61,72,66,65,65,80,72,62,68,81,62,56,68,58,56,82,71,74,78,76,84,94,70,63,72,74,71,71,65,74,66};
int marks_count[101],i;
for(i =0; i < 101; i++){
marks_count[i] = 0;
}
printf("%d",marks_count[1]);
for(i =0; i < 40; i++) {
marks_count[total_marks[i]]++;
}
for(i = 50; i <= 100; i++) {
printf("Marks: %d Count : %d\n",i,marks_count[i]);
}
return 0;
}

Answer 1

plz explain the full program plz