C_PRG_LANG_EX_2.5

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

// Returns position of first met of any symbol from s2 in s1
// Returns -1 if there`s no symbols from s2 in s1
int any(char *s1, char *s2)
{
    for (int i = 0; s1[i] != '\0'; i++)
        for (int j = 0; s2[j] != '\0'; j++)
            if (s1[i] == s2[j])
                return i;

    return -1;
}

int main(void)
{
    char *str1 = malloc(sizeof(char) * 256);
    char *str2 = malloc(sizeof(char) * 256);
    strcpy(str1, "Mother washed the window");
    strcpy(str2, "tad");
    printf("%s\n%s\n%i\n", str1, str2, any(str1, str2));

    strcpy(str2, "ad");
    printf("%s\n%s\n%i\n", str1, str2, any(str1, str2));

    strcpy(str2, "d");
    printf("%s\n%s\n%i\n", str1, str2, any(str1, str2));
    free(str1);
    free(str2);
    return 0;
}