sem3-problem1

#include <stdio.h>
#include <string.h>
#define N 100

int fromHexToDec(char s[]) {
    int ans = 0, i = 0, pow = 1;

    for (i = strlen(s) - 1; i >= 0; i--) {
        if (s[i] >= '0' && s[i] <= '9')
            ans += (s[i] - '0') * pow;
        else if (s[i] >= 'a' && s[i] <= 'f')
            ans += (s[i] - 'a' + 10) * pow;
        else if (s[i] >= 'A' && s[i] <= 'F')
            ans += (s[i] - 'A' + 10) * pow;

        pow *= 16;
    }

    return ans;
}

int main() {
    char s[N];

    scanf("%s", s);
    printf("%d", fromHexToDec(s));

    return 0;
}