View Compilation Error

0_0_26775397_22090.c:5:1: error: unknown type name 'bool'
 bool sushu(int a)
 ^
0_0_26775397_22090.c:15:1: error: unknown type name 'bool'
 bool huiwen(int a)
 ^
0_0_26775397_22090.c: In function 'main':
0_0_26775397_22090.c:46:13: error: expected expression before '/' token
             //    if(i<=505000)
             ^