#include <stdio.h>

unsigned long long int bin_search(int A, int B, unsigned long long int K, unsigned long long int M, unsigned long long X){
    unsigned long long left = 0, right = (2 * X) / (A + B) + 1;
    unsigned long long int tree_amount1, tree_amount2;
    unsigned long long int mid;
    while(left + 1 < right){
        mid = (left + right) / 2;
        tree_amount1 = A * (K - 1) * (mid / K) + A * (mid % K);
        tree_amount2 = B * (M - 1) * (mid / M) + B * (mid % M);
        if (tree_amount1 + tree_amount2 >= X)
            right = mid;
        else
            left = mid;
    }
    return right;
}

int main (){
    FILE *inFile = fopen("forest.in", "r");
    FILE *outFile = fopen("forest.out", "w");
    int A, B;
    unsigned long long K, M, X;
    fscanf(inFile, "%d%llu%d%llu%llu", &A, &K, &B, &M, &X);
    fprintf(outFile, "%llu", bin_search(A, B, K, M, X));

    fclose(inFile);
    fclose(outFile);

    return 0;
}