#include <stdio.h>

int main()
{
    int v1, v2, v3;
    float user_mean, actual_mean;

    printf("Enter 1st value : ");
    scanf(" %i", &v1);
    printf("Enter 2nd value : ");
    scanf(" %i", &v2);
    printf("Enter 3rd value : ");
    scanf(" %i", &v3);
    printf("What is the mean? ");
    scanf(" %f", &user_mean);

    if (user_mean == (actual_mean = (v1 + v2 + v3) / 3.0))
        printf("Correct.  Well done!\n");
    else
        printf("Sorry, should be %f\n", actual_mean);    
    return 0;
}