#include <stdio.h>

char *netaddress(char *ipaddress, char *netmask) {
　int a[4], m[4];
　static char netaddr[16];
　sscanf(ipaddress, "%d.%d.%d.%d", &a[0], &a[1], &a[2], &a[3]);
　sscanf(netmask, "%d.%d.%d.%d", &m[0], &m[1], &m[2], &m[3]);
　sprintf(netaddr, "%s.%s.%s.%s", itoa(a[0]&m[0]), itoa(a[1]&m[1]),itoa(a[2]&m[2]),itoa(a[3]&m[3]));
　return netaddr;
}

int main(void) {
　printf("%s\n", netaddress("192.168.0.1", "255.255.255.0"));
　return 0;
}