#include<bits/stdc++.h>
using namespace std;

int dp[10005];

int main() {
    int A,B,C,D,E;
    cin >> A >> B >> C >> D >> E;
    B -= C;
    dp[1] = D;
    for(int i = 2; i <= A*B; i++) {
        if(i%10 != 0) {
            dp[i] = dp[i-1];
        }
        else if(E <= dp[i-1]) {
            dp[i] = dp[i-1]-E;
        }
        else {
            dp[i] = dp[i-1];
        }
    }
    int ans = 0;
    for(int i = 1; i <= A*B; i++) {
        ans += dp[i];
    }
    cout << ans << endl;
}