**Binary Search approach ** bool canSurpass(int samDaily, int kellyDaily, int difference, int days) { int samSolved = difference + days * samDaily; int kellySolved = days * kellyDaily; return kellySolved > samSolved; }

int minNum(int samDaily, int kellyDaily, int difference) { if (samDaily >= kellyDaily) { return -1; }

int low = 0;
int high = difference / (kellyDaily - samDaily) + 1;

while (low <= high) {
    int mid = low + (high - low) / 2;
    if (canSurpass(samDaily, kellyDaily, difference, mid)) {
        high = mid - 1;
    } else {
        low = mid + 1;
    }
}

if (canSurpass(samDaily, kellyDaily, difference, low)) {
    return low;
} else {
    return -1;
}

}****