digraph G{
"14" -> {"4";"7";}
"32" -> {"23";"31";}
"26" -> {"20";}
"6" -> {"35";"35";}
"33" -> {"20";}
"12" -> {"20";}
"5" -> {}
"4" -> {"7";"37";}
"25" -> {"21";"29";"11";}
"31" -> {"14";"24";}
"34" -> {}
"40" -> {"9";}
"18" -> {}
"28" -> {"7";}
"16" -> {"35";}
"8" -> {"9";}
"introduction" -> {"17";}
"39" -> {"6";"6";}
"11" -> {"36";"5";"27";"18";}
"17" -> {"1";}
"19" -> {}
"13" -> {"7";}
"20" -> {"3";"10";"38";}
"21" -> {"29";"11";}
"7" -> {"40";"8";}
"23" -> {"9";}
"30" -> {"15";"22";}
"15" -> {"9";}
"38" -> {"9";}
"29" -> {"36";"5";"27";"18";}
"36" -> {"19";}
"9" -> {"12";"33";"26";"34";}
"10" -> {"20";"9";}
"24" -> {"7";}
"22" -> {"14";"2";}
"2" -> {"9";}
"27" -> {}
"35" -> {}
"1" -> {"25";"29";"11";}
"37" -> {"28";"13";}
"3" -> {"39";"16";}
}