#include<stdio.h.>
#include<string.h>
#include<math.h>

int main()
{
    double len=0;
    int n,r,i,j;
    scanf("%d %d",&n,&r);
    double a[200][2];
    for(i=0;i<n;i++)
        for(j=0;j<2;j++)
            scanf("%lf",&a[i][j]);
    for(i=1;i<n;i++)
        len=len+sqrt((a[i][1]-a[i-1][1])*(a[i][1]-a[i-1][1])+(a[i][0]-a[i-1][0])*(a[i][0]-a[i-1][0]));
    len=len+sqrt((a[i-1][1]-a[0][1])*(a[i-1][1]-a[0][1])+(a[i-1][0]-a[0][0])*(a[i-1][0]-a[0][0]));
    len=len+3.141*2*r;
    printf("%.2lf",len);
    fflush(stdin);
    getchar();
    return 0;
}

I guess the 8th and 9th line.
The value of radius is a real number instead of an integer, which is considered to be with decimal point. Thus "double r;" "scanf("%d %lf", ..)" maybe works.

Also note.
Is pi=3.141 accurate enough? I used 3.14159 in my AC program