#include "time.h"
#include "stdio.h"
#include "stdlib.h"
int main()
{
int a,b,c,d;
srand(time(0)) ;
while(1)
{
a = rand()%100; b=rand()%100; printf("%d+%d=", a,b);
scanf("%d", &d);
if(d < 0) return 0;
if(d==a+b)printf("Right!");
else printf("Error!");
}
return 0;
}