1010 univariate polynomial derivation (25 minutes)

Analyzing the data read by the end Scanf ()! = EOF

#include <stdio.h>
#include <string.h>

int main()
{
    int a,b;
    int sign=0,w=0;
    while(scanf("%d %d",&a,&b)!=EOF)
    {
        if(b==0&&sign==0)
        {
            if(w==0)
                printf("0 0");
            else
                printf(" 0 0");
        }
        else if(b!=0)
        {
            sign=1;
            a=a*b;
            b=b-1;
            if(w==0)
            {
                printf("%d %d",a,b);
                w=1;
            }
            else
                printf(" %d %d",a,b);
        }
    }
    printf("\n");
    
    return 0;
}