#include <stdio.h>
#include <stdlib.h>
#include <string.h>
int main(){
    char binary_str[100];
    printf("Enter a binary numnber: ");
    scanf("%s", binary_str);
    int len = strlen(binary_str);
    int is_negative = (binary_str[0]) =='1') ? 1 : 0;
    int decimal = strtol(binary_str, NULL, 2);
    if(is_negative){
        decimal -= (1 << len);
    }
    printf("Decimal: %d\n",decimal);
    return 0;
}