#include <stdio.h>
#include <time.h>

void compute( void );

void main()
  {
    time_t start_time, end_time;

    start_time = time( NULL );
    compute();
    end_time = time( NULL );
    printf( "Elapsed time: %f seconds\n",
        difftime( end_time, start_time ) );
  }

void compute( void )
  {
    int i, j;

    for( i = 1; i <= 20; i++ ) {
      for( j = 1; j <= 20; j++ )
        printf( "%3d ", i * j );
      printf( "\n" );
    }
  }