#include<stdio.h>
#include<stdlib.h>
void nhap(double **arr,int dong,int cot)
{
    for(int i=0;i<dong;i++)
    {
        for(int j=0;j<cot;j++)
        {
            scanf("%lf",*(arr+i)+j);
        }
    }
}
double tong(double **arr,int dong,int cot,int kt)
{
    double sum=0;
    for(int i=0;i<dong;i++)
    {
        if(i+1==kt)
        {
             for(int j=0;j<cot;j++)
           {
              sum+=*(*(arr+i)+j);
           }
            break;
        }


    }
    return sum;
}
int main()
{
    int dong,cot;
    scanf("%d%d",&dong,&cot);
    double **arr=(double **)calloc(dong,sizeof(double*));
    for(int i=0;i<dong;i++)
    {
        *(arr+i)=(double *)calloc(cot,sizeof(double));
    }
    nhap(arr,dong,cot);
    int kt;
    scanf("%d",&kt);
    printf("%.2lf",tong(arr,dong,cot,kt));
}