is1.c

#include <stdio.h>
#include <string.h>
#include <ctype.h>
#include <stdlib.h>

int main()
{
	int  i, j;
    char dizgem[] = "123ab4";
    char tmp[1];
    char depo[6]= "";
    for(i = 0; i < strlen(dizgem); i++){
        if(isdigit(dizgem[i]) != 0){
			tmp[0] = dizgem[i];
			tmp[1] = '\0';
			strcat(depo, tmp);
		}
        }
    j = atoi(depo);
    printf("%d", j);
	return 0;
}