switch/case

switch and case
#include <math.h>
#include <stdio.h>
main()
{
    int m; float a=3,i=2,y=2.7,x=1;
    double v=0;
    printf("Vvedite M: ");
    scanf("%d",&m);
    switch (m)
    {
    case 1: {
            v=0.5*a+cos(a)/y;
            printf("%6.2lf",v);
    }break;
    case 5:{
            v=y*y-i;
            printf("%6.2lf",v);
    }break;
    case 7: {
            v=x+(x*x)/-1/3;
            printf("%6.2lf",v);
    } break;
    default: printf("!!!!!!!!!!!!!!!!!NET RESHENIYA!!!!!!!!!!!!!!!!");
    }

}