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

typedef struct{
	int id;
	double math;
	double english;
	double physics;
	double avg;
	double std;
}Grades;

int main(void) {
	
	Grades data[] = {{1,65,80,95},{2,70,68,75},{3,60,100,83},{4,100,55,74},{5,90,85,100}};
	
	for(int i = 0;i < 5;i ++){
		data[i].avg = (data[i].math + data[i].english + data[i].physics) / 3;
		data[i].std = sqrt((data[i].math - data[i].avg) * (data[i].math - data[i].avg) + (data[i].english - data[i].avg) * (data[i].english - data[i].avg) + (data[i].physics - data[i].avg) * (data[i].physics - data[i].avg)) / 3;
		
		printf("id %d avg %.1f std %.1f\n",data[i].id,data[i].avg,data[i].std);
	}
	return 0;
}