#include<stdio.h>

int atoi(char s[]);

int main()

{
  char str[]="12a4c5 ";
  int i=0,n=0;

 while(str[i]!='\0')
   {
      if(str[i]>='0' && str[i]<='9') { n=10*n+(str[i]-'0'); i++; }
      else
       { i++; continue; }
   }
 printf("number=%d\n",n);
 return 0;

 }