#include<stdio.h>
#include<string.h>
char firstNonRepeatingChar(char *s){
    int count[ASCII_SIZE] = {0};
    int i;
    for(i = 0; s[i]; i++){
        count[(unsigned char)s[i]]++;
    }
    for (i=0; s[i]; i++){
        if (count[(unsigned char)s[i]]==1)
        return s[i];
    }
    return -1;
}
int main(){
    char s[101];
    printf("Enter a string: ");
    fgets(s, sizeof(s), stdin);
    size_t len = strlen(s);
    if (len > 0 && s[len - 1]=='\n'){
        s[len - 1] = '\0';
    }
    char result = firstNonRepeatingChar(s);
    if (result == -1)
    printf("-1\n");
    else
    printf("%c\n", result);
    return 0;
}