l6218e eror

i'm compiling the program below in keil uvision 5 and  the eror".\Objects\program.axf: Error: L6218E: Undefined symbol main (referred from __rtentry2.o). Not enough information to list image symbols." appears as result.

#include "lpc17xx.h"
#define d 1000
void delay_ms(uint32_t time);
int main(void)
{ LPC_GPIO1->FIODIR=0xf<<24;
LPC_GPIO1->FIOCLR=0xf<<24;
while(1){
LPC_GPIO1->FIOSET=1<<24;
delay_ms(d);
LPC_GPIO1->FIOSET=1<<25;
delay_ms(d);
LPC_GPIO1->FIOSET=1<<26;
delay_ms(d);
LPC_GPIO1->FIOSET=(1<<25)|(1<<26)|(1<<24);
delay_ms(d); }
}
void delay_ms(uint32_t time)
{ uint32_t i;
while(time--) {
for(i=0;i<16666;i++);}

}

any helpful answer  will be appreciated