diff --git a/dz15.Class b/dz15.Class
new file mode 100644
index 0000000..054fa0b
--- /dev/null
+++ b/dz15.Class
@@ -0,0 +1,46 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+void inp(char *name)
+{
+  int n;
+  FILE *f;
+  printf("n = ");
+  scanf("%d",&n);
+
+  f = fopen(name, "wb");
+  for(int i = 0; i < n; i++)
+  {
+    float x;
+    printf("Input number : ");
+    scanf("%f", &x);
+    fwrite(&x, sizeof(float), 1, f);
+  }
+  fclose(f);
+}
+
+float read(char *name){
+  FILE *f = fopen(name, "rb");
+  float *r = (float*) malloc(sizeof(float));
+  int n = 0;
+  while(!feof(f)){
+    float c;
+    fread(&c, sizeof(float), 1, f);
+    r[n] = c;
+    n++;
+    r = (float *) realloc(r, sizeof(float));
+  }
+    fclose(f);
+  float s = 0;
+  for(int i = 0; i < n - 1; ++i){
+    s += r[i];
+  }
+  free(r);
+  return s/(n-1);
+}
+
+int main(){
+  char *name = "123.dat";
+  inp(name);
+  printf("res=%f", read(name));
+}