combination of numbers - c programming

/*combination of numbers*/

#include<stdio.h>

#include<math.h>

void

main()

{

                int a,b,c,d,s;

                for(a=1;a<8;a++)

                {

                                for(b=1;b<8;b++)

                                {

                                                for(c=1;c<8;c++)

                                                {

                                                                for(d=1;d<8;d++)

                                                                {

                                                                s=(a*a)+(b*b)+(c*c)-(d*d);

                                                                if(s==0)

                                                                {

                                                                                printf("\n combination is %d %d %d %d",a,b,c,d);

                                                                }

                                                }

                                }

                }

}

}

Result:

 combination is 1 2 2 3

 combination is 2 1 2 3

 combination is 2 2 1 3

 combination is 2 3 6 7

 combination is 2 4 4 6

 combination is 2 6 3 7

 combination is 3 2 6 7

 combination is 3 6 2 7

 combination is 4 2 4 6

 combination is 4 4 2 6

 combination is 6 2 3 7

 combination is 6 3 2 7

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