function legoBlocks(n, m) {
    // Write your code here
    const A = 1000000007n;
    const r = new Array(m+1).fill(0n);
    const a = new Array(m+1).fill(0n);
    
    a[0] = 1n;
    for (let j = 1; j <= m; j++) {
        a[j] += (j-1>=0) ? a[j-1] : 0n;
        a[j] += (j-2>=0) ? a[j-2] : 0n;
        a[j] += (j-3>=0) ? a[j-3] : 0n;
        a[j] += (j-4>=0) ? a[j-4] : 0n;
    }
    
    for (let j = 1; j <= m; j++) {
        const n1 = a[j] % A;
        const sum = n1 ** BigInt(n);
        a[j] = sum % A;
    }
    
    r[1] = 1n;
    for (let j = 2; j <= m; j++) {
        r[j] = a[j];
        for (let k = 1; k < j; k++) {
            const n1 = r[k] * a[j-k];
            r[j] -= n1;
        }
        // ATTENTION! in javascript, when the left operand of bigint is negative
        // need to add  +A to be positive, different from python for example
        r[j] = r[j] % A + A; 
    }

    return r[m] % A;
}