>>688
#include <stdio.h>

void func(double x[], double d[], double a[])
{
a[0] = x[0] + d[0];
a[1] = x[1] + d[1];
}

int main(void)
{
double A[2], B[2], C[2];

scanf("%lf %lf %lf %lf", &A[0], &A[1],&B[0],&B[1]);
func(A, B, C);
printf("answer = (%lf, %lf)\n", C[0],C[1]);

return 0;
}