EXTERNAL CLASS BIGNUM;
BIGNUM
BEGIN

    PROCEDURE CALCPI;
    BEGIN
        INTEGER I;
        TEXT Q, R, T, K, N, L;
        COMMENT
        !  q, r, t, k, n, l = 1, 0, 1, 1, 3, 3
        ;
        Q :- COPY("1");
        R :- COPY("0");
        T :- COPY("1");
        K :- COPY("1");
        N :- COPY("3");
        L :- COPY("3");
        WHILE TRUE DO
        BEGIN
           COMMENT
           !  if 4*q+r-t < n*t
           ;
           IF TCMP(TSUB(TADD(TMUL("4",Q),R),T),TMUL(N,T)) < 0 THEN
           BEGIN
               TEXT NR;
               OUTTEXT(N);
               I := I + 1;
               IF I = 40 THEN
               BEGIN
                   OUTIMAGE;
                   I := 0;
               END;
               COMMENT
               !  nr = 10*(r-n*t)
               !  n  = ((10*(3*q+r))//t)-10*n
               !  q  *= 10
               !  r  = nr
               ;
               NR :- TMUL("10",TSUB(R,TMUL(N,T)));
               N  :- TSUB(TDIV(TMUL("10",TADD(TMUL("3",Q),R)),T),TMUL("10",N));
               Q  :- TMUL("10",Q);
               R  :- NR;
           END
           ELSE
           BEGIN
               TEXT NR, NN;
               COMMENT
               !  nr = (2*q+r)*l
               !  nn = (q*(7*k)+2+(r*l))//(t*l)
               !  q  *= k
               !  t  *= l
               !  l  += 2
               !  k += 1
               !  n  = nn
               !  r  = nr
               ;
               NR :- TMUL(TADD(TMUL("2",Q),R),L);
               NN :- TDIV(TADD(TADD(TMUL(Q,TMUL("7",K)),"2"),TMUL(R,L)),TMUL(T,L));
               Q  :- TMUL(Q,K);
               T  :- TMUL(T,L);
               L  :- TADD(L,"2");
               K  :- TADD(K,"1");
               N  :- NN;
               R  :- NR;
           END;
        END;
    END CALCPI;

    CALCPI;
END.