import std.stdio, std.algorithm, std.string, std.string, std.conv, std.array, std.range, std.math;

long A, B, C;
bool can(long age) {
    import std.bigint;
    BigInt x = age / A;
    BigInt y = age - x;
    return x * B >= C - y;
}

void main() {
    auto input = readln.split.to!(long[]);
    A = input[0]; B = input[1]; C = input[2];

    long lb = -1, ub = 10L^^18 + 10;
    while (ub - lb > 1) {
        long mid = lb + (ub - lb) / 2;
        if (can(mid)) ub = mid;
        else lb = mid;
    }
    writeln(ub);
}