// One more thing if you use (//) than everything written become a comment // that will not execute.

#include<stdio,h>;
 void main()
{
    int number_1,number_2,number_3;

   printf("Enter 3 number : n");
   scanf("%d%d%d",&number_1,&amp;number_2,&amp;number_3);

   // We have taken input.

   if( number_1 >;= number_2 )
     // We have check from number_1 and number_2 which is large.
     // if number_1 is large than if will run.
   {
     if( number_1 >;= number_3 )
     printf(" The large number is %d.",number_1);
   else
    printf(" The large number is %d.",number_3);

}
  // We have checked number_2 which is larger than number_1 so.
  else
{

     if( number_2 >;= number_3 )
     printf(" The large number is %d.",number_2);
   else
     printf(" The large number is %d.",number_3);
}
}

or

#include<stdio.h>;
void main()
{
     int number_1,number_2,number_3;

     printf("Enter 3 number : n");
     scanf("%d%d%d",&number_1,&amp;number_2,&amp;number_3);

     // We have taken input.

     if( number_1 >;= number_2 &&amp; number_1 &gt;= number_3 )
     printf(" The large number is %d.",number_1);
 
      if( number_2 >;= number_1 &&amp; number_2 &gt;= number_3 )
        printf(" The large number is %d.",number_2);

        if( number_3 >;= number_1 &&amp; number_3 &gt;= number_2 )
        printf(" The large number is %d.",number_3);

}

Output 1.

Enter 3 number :
12
15
46
The large number is 46.

2.

Enter 3 number :
34
56
32
The large number is 56.

3.

Enter 3 number :
78
65
12
The large number is 78.