#include <stdio.h>

float pow( float base, int exp )
{
  /**
   * 该函数为 base != 0, exp >=1 编写
   */

  if ( exp == 1 ) {
    return base;
  } else {
    return base * pow( base, exp - 1 );
  }
}


int main()
{
  float a;
  int b;

  printf( "input a, b: " );
  scanf( "%f %d", &a, &b );

  /**
   * 默认输入没有错误，且 b >= 0
   */

  if ( base == 0 ) {
    if ( exp == 0 ) {
      printf( "err to calc 0^0\n" );
    } else {
      printf( "0" );
    }
  } else {
    if ( exp == 0 ) {
      printf( "1" );
    } else if ( exp > 0 ) {
      printf( "%f", exp( a, b ) );
    } else {
      printf( "%f", 1 / exp( a, 0 - b ) );
    }
  }

  printf( "\n" );
  return 0;
}