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#include <bits/stdc++.h>
#define init_io(pname) ifstream cin((string)pname+".in"); ofstream cout((string)pname+".out"); ios_base::sync_with_stdio(false); cin.tie(NULL)
#define FOR(i, a, b, in) for (int i = (a); i < (b); i += in)
#define REP(i, a, b) for (int i = (a); i < (b); i++)
#define RFOR(i, a, b, in) for (int i = (a) - 1; i >= (b); i -= in)
#define RREP(i, a, b) for (int i = (a) - 1; i >= (b); i--)
#define trav(a, x) for (auto& a : x)
#define mp make_pair
#define pb push_back
#define f first
#define s second
#define lb lower_bound
#define ub upper_bound
#define sz(x) (int)x.size()
#define all(x) begin(x), end(x)
#define rsz resize
#define mem(a, b) memset(a, (b), sizeof(a))
using namespace std;
typedef string str;
typedef long long ll;
typedef long double ld;
typedef pair<int, int> ii; typedef pair<ll, ll> pl; typedef pair<ld, ld> pd;
typedef vector<int> vi; typedef vector<ll> vl; typedef vector<ld> vd;
typedef vector<ii> vii; typedef vector<pl> vpl; typedef vector<pd> vpd;
constexpr auto INF = (int)1e9;
constexpr auto LINF = (ll)1e18;
constexpr auto MOD = 1000000007;
typedef vector<vi> matrix;
int d = 0;
map<str, int> var; // Variables
vector<str> program; // Program
stack<int> loop_st; // Loop stack
vector<matrix> mat_st; // Matrix stack
void mult(matrix& A, matrix& B) { // B = A * B;
matrix res(d + 1, vi(d + 1, 0));
for (int i = 0; i <= d; i++) {
for (int j = 0; j <= d; j++) {
for (int k = 0; k <= d; k++) res[i][j] = ((ll)A[i][k] * (ll)B[k][j] + res[i][j]) % MOD;
}
}
B = res;
}
void pow(matrix& A, int n) { // A = A ^ n
matrix res(d + 1, vi(d + 1, 0));
for (int i = 0; i <= d; i++) res[i][i] = 1;
while (n) {
if (n % 2 == 1) mult(A, res);
mult(A, A);
n /= 2;
}
A = res;
}
int main() {
init_io("cowbasic");
str input;
while (getline(cin, input)) program.push_back(input);
for (auto& line : program) { // Record variables
stringstream ss(line);
str n; ss >> n;
if (islower(n[0]) && var.find(n) == var.end()) var[n] = d++;
}
mat_st.push_back({});
mat_st.back().resize(d + 1, vi(d + 1, 0));
for (int i = 0; i <= d; i++) mat_st.back()[i][i] = 1;
for (auto& line : program) { // Process each line
stringstream ss(line);
str n; ss >> n;
if (islower(n[0])) { // Variable assignment
matrix M(d + 1, vi(d + 1, 0));
for (int i = 0; i <= d; i++) {
if (i != var[n]) M[i][i] = 1;
}
str tmp;
while (ss >> tmp) {
if (islower(tmp[0])) M[var[n]][var[tmp]]++;
else if (isdigit(tmp[0])) M[var[n]][d] += stoi(tmp);
}
mult(M, mat_st.back());
}
else if (isdigit(n[0])) { // Begin loop
mat_st.push_back({});
mat_st.back().resize(d + 1, vi(d + 1, 0));
for (int i = 0; i <= d; i++) mat_st.back()[i][i] = 1;
loop_st.push(stoi(n));
}
else if (n[0] == '}') { // End loop
pow(mat_st.back(), loop_st.top());
mult(mat_st.back(), mat_st[mat_st.size() - 2]);
mat_st.pop_back();
loop_st.pop();
}
else { // Return
ss >> n;
cout << mat_st.back()[var[n]][d] << endl;
}
}
}
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