Meaning of while (~scanf ("%d%d", & A, & B))

 Have you ever encountered this sentence   while(~scanf("%d%d", &a, &b))
 So what does it mean ？

Example ：

#include<stdio.h>
int main()
{
    
    int a,b;
    while(~scanf("%d%d", &a, &b))printf("%d\n",a+b);
    return 0;
}

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