import std.stdio, std.conv, std.functional, std.string; import std.algorithm, std.array, std.container, std.range, std.typecons; import std.bigint, std.numeric, std.math, std.random; import core.bitop; string FMT_F = "%.10f"; static File _f; void file_io(string fn) { _f = File(fn, "r"); } static string[] s_rd; T _RD(T = long)() { while(!s_rd.length) s_rd = readln.chomp.split; string res = s_rd[0]; s_rd.popFront; return res.to!T; } T _RD(T = long)(File f) { while(!s_rd.length) s_rd = f.readln.chomp.split; string res = s_rd[0]; s_rd.popFront; return res.to!T; } T[] _RDA(T = long)(T fix = 0) { auto r = readln.chomp.split.to!(T[]); r[] += fix; return r; } T[] _RDA(T = long)(File f, T fix = 0) { auto r = f.readln.chomp.split.to!(T[]); r[] += fix; return r; } T RD(T = long)() { if (_f.isOpen) return _RD!T(_f); else return _RD!T; } T[] RDA(T = long)(T fix = 0) { if (_f.isOpen) return _RDA!T(_f, fix); else return _RDA!T(fix); } size_t[] MAKE_IDX(alias less = "a < b", Range)(Range range) { auto idx = new size_t[](range.length); makeIndex!(less)(range, idx); return idx;} size_t MIN_POS(alias less = "a < b", Range)(Range range) { auto r = minPos!(less)(range); return range.length - r.length; } void chmin(T)(ref T x, T y) { x = min(x, y); } void chmax(T)(ref T x, T y) { x = max(x, y); } bool inside(T)(T x, T b, T e) { return x >= b && x < e; } T lcm(T)(T x, T y) { return x * (y / gcd(x, y)); } T euDist2(T)(T[] a, T[] b) { auto c = a.dup; c[] -= b[]; c[] *= c[]; return c.sum; } double euDist(T)(T[] a, T[] b) { return sqrt(cast(double)euDist2(a,b)); } double[] rotate(double[] vec, double rad) { return [cos(rad)*vec[0] - sin(rad)*vec[1], sin(rad)*vec[0] + cos(rad)*vec[1]]; } double norm(double[] vec) { return sqrt(reduce!((a,b)=>a+b*b)(0.0, vec)); } double dotProd(double[] a, double[] b) { auto r = a.dup; r[] *= b[]; return r.sum; } //long mod = 10^^9 + 7; long mod = 998_244_353; //long mod = 1_000_003; void moda(ref long x, long y) { x = (x + y) % mod; } void mods(ref long x, long y) { x = ((x + mod) - (y % mod)) % mod; } void modm(ref long x, long y) { x = (x * y) % mod; } void modpow(ref long x, long y) { if (!y) { x = 1; return; } auto t = x; x.modpow(y>>1); x.modm(x); if (y&1) x.modm(t); } void modd(ref long x, long y) { y.modpow(mod - 2); x.modm(y); } void main() { auto H = RD; auto W = RD; auto S = new string[](H); foreach (i; 0..H) S[i] = RD!string; string ans = [S[0][0]]; long[][] q = [[0, 0]]; while (ans.length != H+W-1) { char c = cast(char)('z'+1); long[][] nq; foreach (nd; q) { auto i = nd[0]; auto j = nd[1]; if (i != H-1) { if (S[i+1][j] < c) { nq.length = 0; c = S[i+1][j]; } if (S[i+1][j] == c) nq ~= [i+1, j]; } if (j != W-1) { if (S[i][j+1] < c) { nq.length = 0; c = S[i][j+1]; } if (S[i][j+1] == c) nq ~= [i, j+1]; } } q = nq; ans ~= c; } writeln(ans); stdout.flush; debug readln; }